Samsung's WMN-5090 wall mount uses motors for tilting and swiveling, and it connects to your television's RS-232 port so that you can adjust the screen's movements via on-screen controls. It can store three positions in its memory, too, which means that you can program it with one setting for when you're watching from the couch, another for when you're watching from the kitchen, and another for when you just want to discourage other people from watching it, for example. The wall mount automatically senses where the wall is to prevent the set from crashing into it.
Unfortunately, this particular model works only with 40- to 52-inch Samsung plasma and LCD sets that are equipped with an EX-Link connection, and it costs about $800. But it'll wow your guests and scare your cat.
For more details on what to look for in a wall mount, read Dan Tynan's Gadget Freak column about them. Dan says that you should plan on spending at least $200 for a low-end mount, $250 or more for one that tilts, and $550 or more on one that articulates--that is, extends out from the wall and swivels from side to side.