When I first heard of the RPi it did sound remarkably similar to the processor and devtool evaluation kits I've used for years. For example the old EB30 Atmel ARM7 eval board I played with in... 1997?
The problem with eval boards is that they are often available only in limited numbers, especially per person, and as the name implies they are sold at big discounts (maybe below cost) to encourage adoption of some processor in hw designs. The people who make them would be less than happy if they were disappearing off the shelves with no prospect of processor sales: and not enough sales of the boards themselves to offset mfring costs.
The RPi is as cheap or cheaper and should not have these political problems. My only concern is that I don't know how they can make the RPi this cheap!
ps. Got a big shock yesterday. Was Googling for info on the RPi and discovered that one of it's leading lights - Pete Lomas - is someone I know. My company owns shares in his company, we use them to design our boards, but sadly the RPi is a separate charitable hobby of his, so I get no shares from that... bummer :-)