Just noticed this...
http://svn.automattic.com/wordpress-mu/branches/2.7
has the most up to date code, but the code at
http://svn.automattic.com/wordpress-mu/trunk
is not the most up to date.
It always used to be that the trunk (second one above) was the most bleeding edge code. Is this a mistake or just a change in organization?
This is mostly a heads up for any others, like me, who blindly upgrade using subversion. It took me a little while to notice this was the route of my non-upgrades.