There's a little bit of new info on this DAC in the June 2010 issue of Stereophile. Looks like it's officially called the rDAC and it's said that the async transfer protocol "in some ways resembles that used so successfully in Ayre Acoustics' QB-9". The DAC chip is the WM8741 and price will be $500.
Given Arcam's reputation I wouldn't be surprised if this DAC turns out to be a solid performer for the price.