Ubuntu Unity , A default Desktop Environment in Ubuntu 11.04.
Already this "unity" in the repos . Its going to work in 10.10 and 10.04 . But efficient performance we can get from it in the 11.04. In the 10.10 & 10.04 we can get unity not in desktop version , its only possible through the Ubuntu Netbook version. At the time of Login you can choose what type of Gnome Environment you want .