How to notify users of blog updates a la Admin Plugin Update notifications?

As far as display goes, the admin code does this in several ways.

1. Via the ‘message’ class for stuff
   that shows once at the top of the
   content area.
2. On the left nav menu,
   either on the Plugins tab or up
   where it says Dashboard.
3. And in the list of themes (or plugins).

Items 2 and 3 get their information via a handshake with the api.wordpress.org server.

Item 1’s code can (mostly) be found in wp-admin/users.php. I would go into more detail, but my wife just told me to ‘Get the hell off the computer because we’re going to the beach.’ Bye!