Upon installing and booting into Windows Vista on his new 20-inch Core 2 Duo iMac, a forum poster known as Peace at Mac Rumors noticed that Vista identified the wireless card in the iMac as a Broadcom 802.11n Network Adapter. Check out the Wikipedia's entry on 802.11n for some details, but it is essentially the next generation in wireless standards, offering increased range (reportedly up to 1/4 mile) and a much faster data thoroughput, up to 50x greater than 802.11b and 10x faster than 802.11a/g.
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.