I love it when people scream "fix" every time they see someting they don't like.
As has been pointed out, Windows Server 2003 is relatively new so it's relatively normal for it to make big gains quickly. It also happens to be the first Microsoft Server solution that's actually affordable, which may well explain some of those 8k or so switches from Linux.
As for the Netcraft stats being "biased" or "inaccurate" it would be nice if people actually did some research before making those accusations. As far as I can tell, Netcraft simply polls the servers and determines what they are running. It doesn't matter if the domain name is registered with a company that runs IIS or whatever, because it's the web server itself that is polled.
It's too early to say if these stats represent a trend marking a turnaround in Microsoft's server fortunes.
