If you follow wireless technologies at all, you've probably read up on the emerging 802.11n standard that new hardware and software will be able to support. A lot have been a bit timid about moving or trying out 802.11n as a replacement for existing networks or to create "new-age" mesh networks, but everyone has been waiting to see how it fares in the real world. There's a very interesting eWeek article that covers new 802.11n devices, and how they actually fare in real-world tests.
Still using the same 2.4GHz spectrum, problems were most often encountered when dealing with other equipment ("legacy" equipment) in the same areas, which cut dramatically into the speeds that N was capable of, sometimes even down to much lower than what modern equipment can get you. In fact, even in simulated environments, none of the hardware was able to reach anywhere near it's rated spec. The fastest of them, with a "theoretical" maximum of 270Mbp/s, barely made it over 112. Then again, with an emerging technology, this happens, and at 112 you are outperforming all shelf-bought customer equipment to begin with. Where the hardware really did shine was in handling multiple streams, in which combined loads for both upload and download looked better. It's definitely worth a read if you are looking forward to using 802.11n, and though no hardware will be readily available for some time yet, it's good to know what to expect. You can learn more about the 802.11n standard here.