As with TWA, Icahn is making a fundamental mistake. He thought that an airline was about airplanes, and he likewise must imagine Yahoo is about websites, or banner ads, or searches. Wrong in both cases. Those businesses aree about people. At TWA, his actions precipitated crippling labor unrest. At Yahoo, the talent won't strike, but it will leave — those who haven't already walked out the door, that is. At Microsoft, too, the thought of taking on all of Yahoo's problems is sparking unease among the executives who would be charged with making a deal work.

Besides Microsoft, it's unclear what Icahn can do for Yahoo, or to Yahoo. Certainly, its board and management need wholesale replacement. Yahoo requires a "product Nazi," one Silicon Valley executive told me, to bust through the company's broken culture of consensus and impose a singular vision on all its efforts. But Icahn is exactly the wrong person to attract that kind of talent. He freely admits he knows nothing about technology; he's just good at opportunism.

As Dan Lyons, writing as Fake Steve Jobs, points out, Icahn's assault will likely start with a character assassination on Jerry Yang, as Icahn did with Motorola CEO Ed Zander, who soon resigned. With Yang's poor performance handling the Microsoft bid, he has sharpened Icahn's knives for him.

Yahoo president Sue Decker should start earning her outsized pay and head this off by taking the lead on handling Icahn. (Yang, the prickly cofounder) is far too tone-deaf to handle such a negotiation.) She should take her cues from former Time Warner CEO Richard Parsons, who played Icahn like a fiddle during his attempted raid on that company; instead of breaking the company up, as Icahn suggested, Parsons arranged for a slightly larger buyback of shares than previously planned.

The lesson from Parsons: The way to handle Icahn is to spend lots of time letting him talk, and then figure out how to pitch something the company was planning to do anyway as his brilliant idea. For Decker, who is widely thought unqualified to be CEO at Yahoo or anywhere else, it will be excellent practice for her future as a perpetual No. 2.

(Photoillustration by Jackson West; photo of Icahn by AP/Mark Lennihan)