According to insiders, Microsoft has code-named its next version of Windows, calling it Fiji. So that's right, Fiji is the next version after Vista, and we're also hearing that after Fiji will be Vienna.
Of course, by the time these products reach the real world marketplace, if ever, they will probably have some other vaguely aesthetic-sounding name. But until then, we'll call it Fiji. Our bets are on an operating system that's not even shrink-wrapped, but web-based, certainly by the time we get to Vienna.
Microsoft's got a codename for Vista successor [the Inquirer]