LPC3000
While this ARM9 device is fast and relatively low cost, right now it does not look like targeted for low volume hobby market. The package with more than 300 balls BGA needs very expensive equipment.
So far Nohau seems the only board. I agree with fireball there will be other boards for a lot less money. However, do not expect a board for 50 or 100 Euro / Dollar any time soon. There are quite some factors like probably 8-layer board and all memory external that make this more expensive than the LPC2000 ARM7-based devices. Then however, the ARM9 provides probably 4 times more performance and if you need the floating point unit easily 10 times more.
Bob