As detailed by AppleInsider Mac OS X 10.7 Lion includes the ability to unlock 450Mbps 802.11n wireless networking in Apple's latest Thunderbolt equipped Macs. The technology depends on Macs being equipped with three send and receive antennas, a feature that Apple's latest MacBook Pro and iMac have.
Apple began incorporating three send and receive antennas in its Thunderbolt-equipped MacBook Pro and iMacs, enabling them to achieve an MCS of 23 and a top data rate of 450 Mbps on 5GHz networks with wide channels. This new capability goes beyond the baseline certification of 802.11n as defined by the Wi-Fi Alliance, which maxes out at 300 Mbps
The 450Mbps transfer rate is supported on newer Macs when connected to modern base stations such as Apple's Airport Extreme or Time Capsule.