Maybe you've already heard that the future of Ubuntu will use Unity instead of Gnome, and Wayland instead of X Server. Since these are new, next versions of Ubuntu will be buggy, and Mark Shuttleworth has expressed that it will take 3 years for it to mature on the desktop starting on 11.04 to be released next year. So, my advice is to stick with 10.04 since it has LTS (Long-Term Support) for 3 years.
In my opinion , his reason with using these technologies, is for mobile devices since it uses uTouch for touch screens like the iPad or Android Tablets, and can also be used for mobile phones because it is much responsive. His decision on Wayland, I guess, since Wayland can also make X Server run as client, it will also support the desktop, but it will take time and patience.
Thanks for supporting Ubuntu.