I can guarantee that Apple will be updating Airport Extreme, and most likely Time Capsule,to the 802.11a/b/g/n specs as well as dual band (2.6 and 5.2 Ghz).

Actual Device Drawings – Second page has the label ‘Airport Express Base Station’
Authorization Letter

Test Results – Check out the top of page 6

You can find the rest of the documents here.