Since upgrading to 2.7.1 my Dashboard has been messed up. It seems to be trying to apply the CSS from the blog to the dashboard. The result is an overlay over text and links over buttons.
At one point, half way down the page, the dashboard seems to draw on 404 content as there's error text.
I've re-installed 2.7.1 by hand - replacing the wp-admin folder, of course, and the effect persists.
I don't know if its related but I can't seem to upgrade automatically as I always hit a timeout error.