I think the bit about RP being used for educational purposes (vs. a PC or VM of Linux) is that you can outfit a classroom with RPs, KBs, mice, and cheap TVs for a bit less money than a room full of computers. Especially when you consider maintenance costs.
It'll also work for the DIY crowd, because it's a fairly complete mini-PC platform -- even the Linux distro is usable out of the box, with the provided images. That removes quite a bit of the uncertainty for those less than familiar with hardware and Linux to get to the point where they can follow online walkthroughs with a minimum of effort. The exception being DVR and IPTV use. Without MPEG2 licenses (read: support), it's useless. (Anyone here dealing strictly with VC-1/AVC yet? Not me.) And I don't think a 700MHz ARM has any hope of handling it in software.
As a hacker's toy, this is not the ideal platform. Sorry, but unless you can get down to the silicon level, it's still a black box. That rubs against the grain for me, especially when it's touted as the ultimate experimenters kit. Look, either I'm allowed to take it apart or I'm not. This halfsees stuff doesn't cut it. Sure, you can peek under the hood, but you're confined to running compatible kernels because someone doesn't want to give away their trade secrets. Fine. Then it is what it is, and (IMO) what it is, isn't for hackers.
But, I think dhunt hit it on the head... What alternatives are there for full-featured GPUs? Technology at this level is just always encumbered by patents. Frustrating how much further a community could take a technology if there weren't always legal roadblocks in the way.