I'm not 100% positive, but from reading this article it looks like the servicing mission to Hubble will be the last flight of Atlantis. After that, it will be decommissioned.
Wow. I mean, I've known we'll be stopping Shuttle flights, and the time is rapidly approaching (let's see if NASA can stick with the 2010 deadline-- I'm actually rather hoping it extends past that a bit to make the gap between the last Shuttle and the first Ares a bit smaller). But to actually hear the news... well, the times they are a'changing.