It does strike me that this thing is very much no huge breakthrough (unless there's something I've missed going on with some special software sauce they are making available)... I mean, yes it's nice that they are selling it at cost price but...

What makes this really different from the Beagleboard?

In essence, both are basically marketing boards for the chip vendor; usually these are much more expensive - $300+ - as they are built in low volume and come with some measure of support as they're intended to help a commercial customer make their own board.

The Beagleboard was the first really decently priced system, which was obviously the result of some apps engineer getting permission to "give this a shot with the hobbyists". The Pi is significantly lower spec than the Beagleboard, and being funded and made by people with no profit requirements, hence it's cheaper, but it's the same thing - barebones uncased computing which won't really appeal to many as it stands.

If they put it in a box and sold it with a mains power supply, boot media, and a cheap USB wifi stick (and did the necessary approvals to make it saleable as an end user product), but charged - say - $50, I think it'd be a lot more interesting. As it is, I suppose they are going to rely on others making boxes for it so that the less hardcore geeks will feel comfortable.