We know that Atmel made it clear that mere mortals can't have the xplain. But according to http://www.atmel.com/dyn/resourc... there is the MC303 xmega board from Atmel (also part of MC323). Avnet lists the ATAVRMC303 board with 26 weeks lead time for $62.
Has anyone spotted the MC303 or MC323 in the wild? I noted the above app. note is dated 10/08, so almost a year for Atmel to bring it out.