Well, "Windows Seven" if you want to spell it all out, but I imagine most people won't.

I like it. Another breathy attempt to be trendy like "Vista" would have just been a bit too much at this point. 7 is utilitarian; clean, simple, software-like. It espouses exactly what I hope the operating system itself does, which is less cruft and eye-candy and more utility and speed. I'm not sure that's actually what we're going to be getting, considering it's built on Vista, but at least they're trying to fool me the right way if not.