Interesting new series of white papers on Wi-Fi interference from Craig Mathias of the Farpoint Group. He set up a couple of clients and attempted various activities (file transfer, VoIP, video streaming) in the presence of interference from various sources (microwave oven, cordless phone, DECT phone, another AP, a Bluetooth headset) and characterized the impairments. His conclusions were that some interference sources can completely shut down some uses (almost all of them shut down video), but that interference can be managed and does not present a long term stopper to Wi-Fi.
Missing from the tests was 802.11n. This should make a huge difference, for several reasons. First, its MIMO operation is intrinsically more resistant to interference, second 11n operates both in the 2.4 GHz frequency range (like 11b/g) and in the 5 GHz frequency range (like 11a) . The 5 GHz waveband is immune from microwave oven interference, and most of the cordless phone interference. Its disadvantage of shorter range is mitigated by the multi-path amplification effect of MIMO.