The nice thing is, if you have a laptop that is powerful enough, it would be just as easy to add a TVTuner card, or whatnot to show TV in the frame. Or you could play a movie if you kept a DVD-ROM drive, not to mention if you attach some sort of wireless keyboard and mouse receiver to the laptop USB port, you could surf the net or do whatever you want with it on the wall.
But just to mention, this isn't exactly the first idea for a picture frame pc.
Although, it is the first time I've seen someone use a laptop.
http://mini-itx.com/projects/pictureframepc/