Fedora 15, now in pre-beta testing, uses Gnome 3 Shell as the standard desktop. This is a controversial decision, much discussed on the mailing lists. Unlike prior versions of Gnome, the desktop no longer looks like a version of Windows XP. There's no menu and there are no files on the desktop. Instead, the top left has the word "Activities". The top right holds icons that show the status of various system things like connection status. Where do you start? It all comes together when you put the mouse over the word "Activities". The screen shows a "favorites dock" on the left and tiles all open windows. There are two new words on the screen, Windows and Applications. Windows is the view of open windows; Applications is a grid of installed applications.
When I first tried Gnome 3 Shell, it was inscrutable. Now that I've become a Mac user, it's very familiar. The one thing it lacks is a permanent on-screen place to show what's happening and links to my favorite applications. Thanks to someone on the Fedora test list, I've found Avant Window Navigator and completed my Mac desktop on Linux. For me, it's the best of both worlds. I'm using the new, clean desktop from Gnome and I don't have issues when moving back and forth between my two Linux machines and my MacBook.
For my fellow Fedora users, "yum install avant-window-navigator awn-extras-applets".