The sadists over at iFixit have taken apart an Airport Extreme 802.11n to see what's going on on the inside. What is on the inside? Well, just a board, some wires, and Ethernet ports. No little 802.11n Gremlin like you would have thought.
Their benchmarks, however, show that the claims of 5x performance and 2x range are actually low! iFixit found a 10x performance increase and a 3x usable range increase using the 802.11n over 802.11g. If you're looking for an unboxing, check that out here as well.
Airport Extreme 802.11n Disassembly [iFixIt]