I just upgraded to version 2.2.2 on this blog thursday and what happens the day after I upgrade? Wordpress releases version 2.2.3, proving Murphy correct once again.
As this is a security update fixing at least one pretty nasy hole, you really should upgrade to 2.2.3.
If you want to know exactly why you should upgrade here are the bugs and problems fixed with this release and which specific files were changed.
Yep, I guess that is how it works. Once you get an update installed, the next one comes along.