If I leave my cell phone near my computer speakers I will hear
> occasional buzzing, clicking, etc. Before the phone begins to ring, I
> hear a dah..dah.daahhhhh. I know this is RF interference being picked
> up by the amplifier in the speaker. If one were to record this sound
> with a microphone at 11 or 22Khz, would it be possible to obtain any
> information (usable signal) from the recorded audio?
Odds are that you have a GSM provider such as Cingular or T-Mobile. You'll hear the "dat-dit-dit-dah-dah-dah" sound occasionally and will usually hear it prior to your phone ringing.
As to what you could get with this the answer is pretty much nothing. GSM and TDMA are encrypted so you wouldn't be able to gather much of any information.