Details of the frequency's that different equipment operate on is in this thread:
http://www.cableforum.co.uk/board/sh...wave+frequency
But from what I understand 2.8Ghz is used in microwave ovens because it has a peculiar effect on the bonds between hydrogen and oxygen atoms, in effect it makes them stretch and contract and ultimately heat your cuppa. The info I have says that this is specific to this frequency so your WAP/router shouldn't cook you
Although thinking about it your wireless network operates at 2.4Ghz, which is closer to that magic pasty cooking frequency than DECT or the upper mobile networks!! I'm sure someone somewhere is doing some research into it