Update: no need for this plugin anymore, the new WordPress handles updates on his own :( .
Usually when the new version of WordPress is out, you have to download the latest zip (or tar.gz), unpack it, upload everything, and run upgrade. You can help yourself with uploading the zip file to the server and unpack it there, but you have to have shell account and know a bit of console commands.
There is another way of upgrading to the latest version, and that involves usage of Subversion. This gets the latest of files but you still need the console. The command is:
svn co http://svn.automattic.com/wordpress/trunk/
So, to help with the upgrading process, I’ve developed the SVN upgrade plug-in. It uses the phpSVNclient and some other classes by Cesar, who posted it on PHP Classes. I took it and made the plug-in firstly for my CMS, and it works great. Than I saw that the WordPress can be obtained via Subversion, so I decided to make svn upgrade available to all.
SVN upgrade uses database (wp_svn table) in which it stores the latest repository revision. If a new revision is out, you can do the upgrade, otherwise it will tell you that it is on the latest version.
Oh, and I have just tested it, again. 8061 is out! Bleeding edge! wp-login.php just got debugged, or something, and i have it! With just one click! Great!