In addition to the GNOME3 PPA and Rico's PPAs, we have a new experimental PPA for raring which we are using to upload GNOME 3.7:
Code:
ppa:gnome3-team/gnome3-staging
As Ubuntu's efforts are focused on GNOME 3.6, this PPA doesn't have the same level of quality and testing that goes into the regular GNOME3 PPA. GNOME 3.7 itself is still a work in progress.

I just uploaded gnome-control-center/gnome-settings-daemon 3.7.3 to the PPA. The most obvious regression it introduces is that external panels aren't working (they've never been officially supported by GNOME).

I've also uploaded gnome-shell 3.7.3. When I tested it I saw two major bugs: the user menu in the top right is missing, and using the keyboard to enter text in Shell dialogs (like Alt+F2, authentication prompts, unlocking the screen or the Activities Overview) doesn't work reliably. I reported both those bugs to GNOME but we've not figured out what the root cause is yet.

Unless you like broken things, you probably don't want this PPA yet. At least make sure you know how to use ppa-purge first.

On the other hand, it would help us and the GNOME developers out if you would give the PPA a try so that we can find and fix bugs before 3.8 is final. If you're interested in packaging, this is a great opportunity to get involved to help package the GNOME milestone releases.