If you weren’t able to make it to Pubcon in Austin (sux to be U!) then you should know about their announcement. They’re releasing Google Friend Connect. It allows plugins to manage people’s logins to forums and blogs to post and comment which reference a single profile rather than having to sign up to every site you want to post or comment on.
They currently have 3 plugins built (Drupal, WordPress, and phpBB) but welcome anyone to build additional plugins for other sites.