PyGTK 2.7.3 has been released
I just put up a tarball of PyGTK 2.7.3 on ftp.gnome.org, it can be fetched from:
ftp://ftp.gnome.org/pub/GNOME/sources/pygtk/2.7/
once the mirrors have synced correctly.
What's new in 2.8?
See the wiki page for an overview of news in 2.8:
http://live.gnome.org/PyGTK/WhatsNew28