The final 802.11n specification is projected to be released in June 2009. The 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.
Apple first began shipping 802.11n cards in the MacBook Pro and the Core 2 Duo 20-inch iMac in October 2006. In a piece in January 2008 I complained about how the Airport Express was holding up the (wireless) revolution and how 802.11n is practically required for things like wireless data migrations and Time Capsule backups.
The updates APE, which was widely predicted, brings the portable Airport Express up to par with the the Airport Extreme which went 802.11n. My question is why new hardware? Why couldn't Apple offer a firmware flash update to the 802.11n standard like they did with the Airport Extreme in January 2007? I'd gladly pay the $5 "n-tax" for that.
Now the only Mac left that's non-n is the Mac mini.
So, are you buying the new APE?