Are these actually still in "beta" chips, or are these chips left over from the completed beta test? The latter is pretty common; once a company feels like their chip is working pretty well, and like they have a good handle on anything remaining that's wrong (do be sure to read the errata), they'll take the chips that were manufactured during the test period and start plopping them on development boards and/or selling/sampling them to "early adopter" customers. IIRC, TI, Atmel, and Freescale are all "well known" for shipping development boards with "X" version chips ("engineering version")
This is not the same as actually being part of the beta test. :-)