It may be Apple's worst-kept secret, but it's a secret nonetheless: the company is including wireless cards in the new MacBook Pro Core 2 Duo that support the draft 802.11n wireless protocol.
The final 802.11n specification is projected to be released in December 2006 but that could slip as far back as 2008. The 802.11n spec supports both 2.4GHz and 5GHz frequencies and typical data rates are expected to be 200Mbit/sec with a maximum of 540 Mbit/sec. Range is expected to be ~160 feet.
The real data throughput is estimated to reach a theoretical 540 Mbit/s (which may require an even higher raw data rate at the physical layer), and should be up to 50 times faster than 802.11b, and well over 10 times faster than 802.11a or 802.11g.
The picture at right is courtesy of iFixIt.com who has posted a complete take apart of the new C2D MacBook Pro including pictures of the "draft-n" wireless card. In the picture you can clearly see three antenna cables coming into the top of the adapter, previous generation MBP's have only two cables.
Apple also shipped a draft 802.11n wireless card in the latest Core 2 Duo 20-inch iMac. Although Mac OS X doesn't take advantage of the faster card, Microsoft Vista identifies the card as a Broadcom BCM4321-series which Broadcom promotes as the "first IEEE 802.11n draft-compliant Wi-Fi solution."
While not confirmed, it is widely believed that Apple's forthcoming iTV device will also ship with 802.11n to support the greater bandwidth required to transmit video (especially HD) wirelessly.