Gnome 3.4 is in Beta. It looks good. But when can I uses it? As I'm running Debian Squeeze, not in the near future. Fortunately, Fedora 17 is in Alpha, and will have Gnome 3.4. This means I will be able to try out Gnome 3.4 in a couple of months on a Live USB, or even install it if I want to sacrifice the stability of Debian for the minor bugs and frequent updates of Fedora.
The is the Linux dilemma: a stable system or the latest desktop (and software).
I just hope that by the time Debian Wheezy comes out, Gnome 3 has matured. I'd hate to install Wheezy only for Gnome to issue a new release full of new features and bug fixes, meaning I wouldn't get it for two years till the next Debian release.