One of Facebook's great virtues has been its snappiness, and reliability. Personalized services are technically demanding, as Facebook's sluggish predecessor, Friendster, discovered to its cost. So, it's a little embarrassing that Mark Zuckerberg's new "platform" — an environment for other companies to build mini-sites within Facebook — is down this morning. There's an annoyingly cute cartoon and message, claiming the site's down for maintenance. Sure, yesterday's announcement of new third-party offerings, such as the iLike music recommendation system, was a critical success. The tech bloggers have gone embarrassingly ga-ga for Zuckerberg's initiative, though maintream journalists, with wider audiences, have had a hard time explaining why a "platform" is so exciting. But I counted only 1,800 or so users for the most popular app, iLike, so it's not as though Facebook should have been so completely overwhelmed.