GNOME Shell 2.29.0 delivers a new message tray showing notifications sliding into the bottom of the screen, a status area for past notifications, the ability to set your presence to the user status menu, switching the overview between a grid and linear view of workspaces, the initial version of the extension system, a new workspace switcher pop-up, most of the existing relevant code has been ported to CSS, and many other visual improvements. If the mentioned improvements are not enough to suit your fancy, GNOME Shell 2.29.0 also has many improvements to the application switcher that's used when Alt-Tab-ing, behavioral improvements, and enhancements to the GNOME Shell Toolkit. GNOME 2.29.0 is also expected to perform better and has a whole host of bug-fixes.
The GNOME Shell 2.29.0 release announcement with its lengthy change-log can be read on the gnome-announce list. GNOME Shell is available with GNOME 2.28 and the forthcoming GNOME 2.30 release in March, but it will be officially christened with GNOME 3.0 come September.