Ubuntu 10.04 LTS has so many mac os x touch, and its totally my opinion 🙂 . I just completed the Ubuntu 9.10 to Ubuntu 10.04 upgrade process. The look is so clean with new set of wallpapers. So fast while accessing applications and drives. For the past 1 hour no system hangs i must wait for 1 week atleast to check whether there is any crash or system hang occurrence is happening.
If you are still in ubuntu 9.04 or 9.10 then you can really think about upgrading it to the latest one. Testing Gwibber a social client to use facebook, twitter etc., in your desktop itself. Will come up with a good review soon.