The bandwidth does not relate to the amount of data that will be transmitted directly. Protocols such as TCP/IP and Appletalk wrap the data with headers and trailers to ensure that the data is transmitted in the right order and that packets are re-sent if they are malformed, lost, etc. Appletalk is a particlularly slow protocol, but is fairly resilient one. TCP/IP again is not the speediest or most lightweight of protocols, but does give resilience. Other protocols are faster and more lightweight, but usually at a cost of lost packets, etc.
Just look at 56k modems - you don't get 56k through that medium, so you can't really expect 11MB through airport. You won't get 10MB/100MB through a hardwire ethernet connection either.
iBook SE Graphite OSX
iMac DV+ OSX
Airport Base Station
Bluetooth and t68i