According to SciFiWire – http://www.scifi.com/scifiwire/index.php?id=58910
This 5th season will be the last for Stargate Atlantis, but they have the go-ahead to make a 2-hour movie. And the SciFi Channel says they will air it before it goes to DVD.
While I’m excited that Atlantis will get to make a bigger budget movie, I’m really going to miss the weekly fix that no other science fiction show is filling right now. At Comic Con, they mentioned another Stargate spin-off in the works. But who knows when that will happen.