Here's another interesting kickstarter project - Udoo
It takes the best elements of Raspberry Pi and Arduino, applying them to one micro-controller PCB. In this case though, the device has the power of 4 Pi's.
It's fully compatible with Arduino exansion modules too.
There's no end of these mini boards coming out and it's tricky to decide whether or not it's worth getting one.
I'm planning to stick with my Pi for the time being until the market settles.