Gnome 3 will be released in September 2010 integrating a stable version of Gnome Shell (currently in active development)!!!
The first noticeable change in GNOME Shell is that the two panels of GNOME 2 are replaced by a single black panel at the top of the screen
The most important of the innovations seen in GNOME Shell is the Activities overview mode which dedicates a full screen to all the different ways in which the user can switch from doing one thing (an activity) to doing something else.
Gnome Shell is a really cool innovation on Gnome. It provides core interface functions like switching to windows and launching applications. GNOME Shell takes advantage of the capabilities of modern graphics hardware and introduces innovative user interface concepts to provide a delightful and easy to use experience.
Is really different from the previous Gnome Interface and it take a bit of time for have full controll of this new interface but you can also see lot of improvements !