Out-broadcasting
Out-Broadcasting is a term used to explain the process by which 802.11n base stations can swamp or overwhelm existing 802.11b and 802.11g wireless networks.
Overview
Some companies are producing routers such as Netgear's MIMO RangeMax and they can allegedly impact on existing wireless networks by out-broadcasting them which then literally causes so much RF interference that the existing wireless network is unusable.
Explanation
In order to achieve increased speed, wireless routers based on the proposed 802.11n specification (the first draft of which has been rejected by the consortium for just this issue, among other things), use more of the sidebands on the 2.4GHz band than the individual channels used by either 802.11b or 802.11g (in the US there are 11 such sideband channels allowed).
There are only 2 channels being used in 802.11n routers, and these channels are so wide that they are knocking off 802.11b and 802.11g routers in the same area.