If you've eaten beef in the U.S. that was listed at "Kobe beef", it almost certainly isn't. However, as of late 2012 a tiny quantity has been imported into the United States. According to Forbes Magazine, and the Wynn Magazine as well, as of December 2013 Wynn has become the "first US end-user certified by the Kobe Beef Council as an authorized restaurant partner" selling true Kobe beef (yeah -- the stuff from Hyogo prefecture).
I thought it would be interesting to compare it to other Japanese wagyu beef, but haven't been able to get any detailed information out of Wynn. After three phone calls, two emails, and a comment on their Facebook page, I've found out that: yes they offer it at Mizumi, and maybe elsewhere; they have no idea what is the quality level, or BMS value, of the beef being offered.
Does anyone have any additional info?