There is another type of product that is causing a lot of concern because of the amount of interference to the radio frequency spectrum that they cause.
These are the PLA (Power Line Adapters) which are really broadband radio transmitters which use the house mains cables to transfer digital data. Unfortunately a side effect is that the house wiring acts like an aerial and the radio frequency energy does not remain in the house wiring, but radiates some considerable distance, maybe as far as 1km.
One of these (Comtrend) is supplied as part of the BT Vision package. Another one made by Belkin operates as high as 350MHz so it can cause interference to a variety of aviation frequencies (ATC, ILS Localiser etc). It is possible due to harmonics and and a process called Intermodulation for their interference to affect even higher frequencies.
They should be banned under the UK EMC regulations, however the EU is letting Ofcom (the regulator) off the hook on this one, as to ban them would get in the way of "Big Business".
If you find that your RB seems deaf, or that your wireless keyboard is acting strange look around for PLA's either in your house or your neighbours.
Cheers
S.