If this is true, and Windows isn't simply mistaking the hardware it's reporting (like that's never happened before), this is quite an intriguing move for Apple, as the actual 802.11n protocol has quite a ways to go on its journey to becoming ratified as an industry standard. Further, this is dumping fuel on the rumor fire that Apple will be using 802.11n in the iTV to achieve HD streaming. After all, the upcoming device has all the fixins for handling HDTV, and Mac Rumors is also observant in pointing out that Mr. J said the device uses "802.11" on stage, without specifying which version.
That's about all we have for now. We'll keep our eyes out for iMac and Mac Pro dissections to see if anyone can find cold hard evidence.