GNOME 3.7 development is well underway, with the 3.7.3 snapshot that is marking the third release of this development cycle .
To compile GNOME 3.7.3, you can the jhbuild  modulesets  (which use the exact tarball versions from the official release). A slight complication is that gnome-control-center 3.7.3 does not build against network-manager-gnome 0.9.6.4 (you need current master), so the network panel can not be built.
This release is a snapshot of early development code. Although it is buildable and usable, it is primarily intended for testing and hacking purposes. GNOME uses odd minor version numbers to indicate development status.
For more information about 3.7, the full schedule, the official module lists and the proposed module lists, please see our colorful 3.7 page: http://www.gnome.org/start/unstable