One of those is Cal Henderson, Flickr's longtime director of engineering (left). AllThingsD's Kara Swisher reports that he's left Flickr and is working on a startup with Flickr cofounder Stewart Butterfield, who quit Yahoo with a bizarre resignation letter last year.

That's not all he's up to: We hear he spoke at some length with a Google recruiter at a party Saturday night. In an IM conversation, Henderson admitted he went to a party "with some folks from Six Apart [the blog-software company] and Flickr," but denied he'd spoken to anyone from Google.

Google's interest in Flickr's people is of long standing. Before Yahoo bought Flickr in 2005, Butterfield and his cofounder, then-wife Caterina Fake, flirted seriously with selling to Google. (In the small-world department: Megan Smith, the Google executive who championed a purchase of Flickr, is married to Swisher, the blogger who broke the news of Henderson and Butterfield's new startup.)

So if Google can't have Flickr, why not have its best people? No surprise that they're talking — and no surprise that Henderson's playing hard to get.

About as ridiculous as charging tens of thousands of dollars to teach students how to pick up a phone, ask people questions, think about what they tell you, and write. You know, like journalism school!

Update: Lest you scoff at Birmingham City University's new-media credentials, Cal Henderson, the Flickr engineer with a surprisingly numerous geek-girl fanclub, would like everyone to know he's a proud alumnus. "No Twitter course in my day though," he adds, with a tearful emoticon.

More spy photos? Send them in.

Social networks — the kind Henderson and Waldman work on when they're not using them to flirt — are supposed to expand our worlds. Yet these websites' real effect is to shrink them. Who'd want to start anything with anyone who's not already registered on all the same websites you use? The training time to explain the twee etiquette of Web 2.0 is a barrier to entry more fearsome than any Google or Microsoft might dream up. It can only lead to San Francisco's insider scene becoming literally inbred.

(Photo by bees))

And here Mr. Henderson shook my hand and didn't mind at all when I said it was really his longtime companion Tom Coates, part of the Fire Eagle team and old queer hand of the blogosphere, whom I came out to meet. "We're here in my circle of exes," Culver continued. "And I have one to toss back at you," I added.

The rest of the evening is lost in a botched Flip video file sync — no footage for you — and a flurry of text messages wherein I tried to locate the guy getting a handjob in the men's room at the end of the night. No help from Fire Eagle there! Tip me if you know who the lucky jack was? (Photo by Andrew Mager)

That was Jamie Zawinski, the Netscape engineer who helped "free the lizard" by open-sourcing Mozilla, even though he apparently offered up his SoMa nightclub, DNA Lounge, for the event. Zawinski did, however, build a time capsule of the early Web — including early iterations of the Mosaic browser and website — for those of you who couldn't make the party but would like to wallow in the nostalgia. Who did show up? Dozens who RSVP'd after Valleywag's calendar listing yesterday, forcing Mozilla to open up the bar when the drink tickets ran out. Photos, including our own Owen Thomas making nice with Anglosexual Flickr engineer Cal Henderson, by Randal Alan Smith.

You kidding? Culver knows better than to trust you people. The Pownce founder's new man is Flickr's Cal Henderson, according a tipster who implores us: "Trust me. You don't get a better source outside of Leah or Cal themselves." Another tipster gives us this eyewitness account from the Future of Web Apps conference in Miami:

I expected that Leah Culver story three weeks ago, since she was all over Cal Henderson at the FOWA beach party. In fact, it was so obvious I expected it to be headlining Valleywag the next day, not the Kevin Rose/Julia Allison stuff (which was barely anything).I don't know if any of you were actually at that party, but she was stumbling around following Cal like a little lost puppy, landing occasional kisses and tugging on his shirt to go out to the beach where they did who knows what. It was almost comically blatant.

I tried to hit on Leah Culver at a party not too long ago but that ended in EPIC FAIL. Apparently she was dating Andy Smith from Jaiku at the time. I have no idea if that has changed, but I wouldn't doubt it.

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(Photos by hyku, hyku and MrTopf)

Strikeout! Mullenweg showed up at the last minute. One wonders: Was the recently minted millionaire dealing with fallout from his nasty Twitter fight with Six Apart's Anil Dash? Or was he just calling his broker? (Mullenweg later told me he just went to the wrong green room.)

Flickr's Cal Henderson says "fuck" a lot, which would seem to come with his job. "I'm Cal Henderson from Flickr, the kitten-sharing website" is how he introduces himself. He admits that one Flickr breakdown came about when he failed to use a basic Linux utility, df, to measure if he had enough storage available — a problem when you serve terabytes of photos. Still, it's a good problem to have. "A lot of people can ignore scale forever," he notes — because they never get enough users to bring their site down. "We serve 32,000 photos a second," says Henderson.

"One of the things I don't like about Web 2.0 is you as users want your data to be available, to stay up forever," says Digg architect Joe Stump. "As an engineer, I hate that."

Most of the panelists favor open-source software and cheap hardware. "Buying enterprise means they don't put their prices on the Web," says Mullenweg, the creator of blogging software WordPress. "It means you have to talk to someone with slick-backed hair for 30 minutes. It's uncomfortable."

If you can get over that, says Henderson, "the easiest way to solve scaling problems is to throw money at it. When you're a startup and you don't pay your engineers, then engineering is cheap and hardware is expensive. If you're paying for engineering time, that's expensive."

Stump takes a question from Pownce creator Leah Culver: "Where do you find your bottlenecks?" Stump's answer: "Bottlenecks never have to do with your [programming] language." Henderson instantly retorts: "Unless you're using Ruby." (Ruby is the language used by Twitter, among others, and some blame it for Twitter's outages.) Stump's comeback: "It's always your database or your file system."

StumbleUpon's Garrett Camp suggests testing new features on a small set of your audience, rather than everyone at once, so you test under real conditions but don't afflict buggy code on all of your users at once.

"When we look at the site, we ask, 'What don't we have to do right now?'" says Digg's Stump. Avoiding real-time updates helps avoid bottlenecks. Henderson says Flickr sometimes shows photo pages that are a minute old — again, to minimize load on the site.

That's a rare moment of agreement between Henderson and Stump. The two are back to sparring in minutes. Henderson's comeback to an obscure point Stump makes: "I don't want to work at Digg." Stump then ribs him: "So, Cal, you're moving over to Microsoft technology soon, right?" "Yes, we're moving over to .NET and SQL Server," is Henderson's deadpan response. That's the last zinger before the show wraps up.

It's an old photo. But now it appears at fancytrousers.com. Kevin explains why the next-generation Internet crafters put their resources toward the above.

Kevin Burton: we were giving them crap about how you can't call them knickers and trowsers
since fancy pants != fancy trousers

Valleywag: them? the brit contingent?

Kevin Burton: y[es]
"them"
we were giving htem shit since British sounds so funny
knickers, bollucks, trousers, etc
minga
shiite

The most brilliant minds of emerging tech converge on one space, and you get...knickers and bollocks.

Fancy Trousers [fancytrousers.com]