I am not sure how safe this plugin is to use, but it definitely seems like one to keep an eye on. Its called InstantUpgrade, and that’s its function.
There’s no doubt about it: Upgrading is annoying. You must download the new version, unpack it, delete the old files, copy in the new files, run an upgrading routine.
Now for WordPress users, much of this is obsolete. The InstantUpgrade plugin provides is a easy and safe way to upgrade your WordPress automatically with a single click! (It is to say that it needs some preparations, though.) You can upgrade to the latest WordPress version, or you can upgrade to a version of your choice.
The InstantUpgrade plugin is Free Software available under the GNU GPL.
If it makes upgrading any easier, and doesn’t compromise the security of WordPress, then why isn’t this already in the core of WordPress? Try out InstantUpgrade and let me know how it goes.