GUI time line [via Haddock]. Very good, lots of linked information and screenshots.

Interesting to see that the NeXT OS and Windows 3.0 were contempory -- how could you even go about writing Windows if you knew that this other, spectacular UI was out there?

From an Apple Mac OS X fan perspective, I'm a bit concerned about the impending launch of Windows XP: They're sticking with the familiar Windows 95 UI, fixing it, tweaking it, and enhancing it in the right places (the way they deal with photos is superb). It's becoming mature. OS X on the other hand has thrown away a lot of the mature aspects of NeXT (on which is was based), and of Mac OS X Classic -- they're going to have to do a lot of basic coding work even before the point where innovative things (like live folders, and enhanced file metadata for MP3s/emails/etc in the file system) can be worked in.