I'm A Banana
Potassium-Rich
See, this is the sort of advice I'm expecting from Heroes of Horror. I have something I want to do that has only one or two hard-n'-fast requirements. The advice, to use the term loosely, is "well, you can't do that with D&D--it's too over-the-top, which according to our demographics is how everyone but you likes it--but you can do something else that we think is pretty cool..."
Your hard-and-fast requirement, however, is basically railroading. "I want them to fall for my nefarious trap and be trapped because that's totally cool." And banning teleport is attractive because it, in many ways, thwarts that railroading.
If you're looking for paranoia and claustrophobia, I and others have given you ways to inspire a feeling of paranoia and claustrophobia with or without Teleport (Third Wizard, as usual, has some really golden advice). If you're looking specifically just to trap your PC's without them having methods of thwarting that, the advice is stickier (basically relating to giving the NPC's more firepower, the unhallow/dimensional achor combo, antimagic fields, or whatever), because that removes some choices and powers from the usual choices and powers that PC's have, and taking away PC choice is not something the game in general is interested in.
If you want to ban or introduce mundane methods of thwarting Teleport, go for it and have fun. But if you're asking how to make PC's fear for their lives and feel trapped, even when they can Teleport, without nerfing them, your answers are all over this thread.
Do you want to inspire an emotion, or execute a particular plot device that will inspire that emotion? In the first case, I'd say love the bomb and work withuot nerfing. In the latter case, nerf away if your players won't care.
