I upgraded to 2.7 and all is fine except I can't log out of my admin area.
I have already visited http://codex.wordpress.org/Template_Tags/wp_logout_url and changed the wp_logout_url for my theme. I changed it in the comments.php file and now the logout is working fine from the front-end of my site when I log out (e.g. as a commenter).
But it's in the header of my admin area that I can't get the proper URL for logging out. Which means that, when I click 'sign out', I get the 'You are attempting to log out...' message, with a 'Please try again' link back into the admin area.