will not be rolling out until the first half of 2010, but work is already underway on this major GNOME update that is the first to bring some radical changes in a long time. One of the major components of GNOME 3.0 is the GNOME Shell. The GNOME Shell will begin handling some of the responsibilities that previously was done by the window manager and GNOME Panel in GNOME 2.xx while offering a modern graphics experience.
There's still much more work left to be done to GNOME Shell over the next several months, but a new development release is available for interested developers and testers. GNOME Shell 2.27.1 was released last night and is described as "GNOME Shell provides core user interface functions for the GNOME 3 desktop, 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 visually attractive and easy to use experience."
Among the changes in this release is new search behavior, further visual improvements, support for user interface translation, an improved zooming animation, UI tweaks, and code cleanups are a partial list of what's new or has been changed.
The GNOME Shell 2.27.1 release announcement can be read in full on the GNOME announce list