I used perfectins to install ours. Omar was great. I think it was $250, which included installing the mount, adding a new electrical outlet, and passing the wire through the wall down to our entertainment center.

I look him up via angie's list, but i think this is his website: http://www.perfect-ins.com/

One of the entrepreneurial non-Ivy grads from another thread who report earnings of over "500 K".

I've used Mr. TV Mount before. They did a great job, but the installation was rather difficult. One TV was mounted on a wall between townhouses, there are no wood studs there. the other was mounted over a fireplace. They hid all of the cables (cutting out the drywall, routing them through the ceiling and such), added a new power outlet behind the TV over the fireplace, and did a great job. At first I though the price was rather expensive, but it took 2-3 guys about 6 hours to do the installation and they were working the entire time. Definitely not something I could have done myself very easily.

Mrtvmount.com