There are two built-in types of Automatic Turrets. They are the TeamCannon and the MinigunCannon, which is a subclass of TeamCannon. These types of actors are most frequently used in maps for the Capture the Flag and Assault gametypes, as well as a few good custom gametypes. And most importantly, for a stress reliever: just put 20-30 of them across CTF-face, add bots, spectate, and enjoy!
Ars-Magna: Random Tidbit–you can kill the turrets, and even better, you can telefrag them!
A note on those turrets in CTF games: The CTF game code has a major bug concerning Pawn (UT)s without a PlayerReplicationInfo like Unreal monsters or the turrets. Every time a non-player pawn (neither Bot nor PlayerPawn) kills a player an Accessed None error is logged and also Bots might get confused because of the badly written CTF code.
ProjectX: I think we should put all of the sections of the actor's properties in pages like this, because people will know what they are, yes, but they won't know how to use one. I would do it personally, but i don't know how to use them either!