Ubuntu Linux: job well done
Don't get me wrong: I think that Mac OS X is the most productive operating system for my work (software design and implementation, writing). That said, I find it exciting that Free Software alternatives are getting so good. Except for being able to edit video movies, Linux comes close to OS X for just about everything that I do. Since the final target/deployment platform for just about everything that I do is a Linux server, I might decide to do more development under Linux in the future (back to the future - I did almost all of my development on Linux up until a few years ago when someone gave me a Mac OS X box).
Anyway, the Ubuntu Linux team did a fantastic job getting a good looking (great fonts!) configuration set up on the Live CD. I browsed the web with FireFox for a while, used OpenOffice.org, etc. Exciting stuff.