Can't wait to get hold of one of these either. I see them as being more capable than an Arduino, but not as complex as using an FPGA so they should fill a nice gap.
I missed out PIC coding so don't know how they fit in the performance/functionality line, but I'm guessing the integrated peripherals and the ability to run a real OS is going to open up a load of opportunities. I was a bit disappointed when I realised how hard it would be to get a video display from an Arduino (and also have it do anything else) so I'm really looking forward to this.