Theres nothing in their T&C/privacy policy and other voice and general acct user agreements that notifys users of such. just read all of them.

Can't see how such obtrusive data mining, and arguably 3rd party monitoring of telco communications w/o conversees notification would be legal. Never had it happen to me with gv, and i doubt theyre doing that for the legal reasons i just pointed out.

Now android phones, or google maps on your n900 may allow then to know your location, but other than that i dont see it happening with a n900. And voice conversations content based targeted advertising seems even more unlikely under any circumstances.

Android may give them your location derived from gps,wifi aps, and cell tower data, as well as the callers, but they say they only use that info to provide you with gv service, not ads. But thats completely different than sip audio content mining, which is not only illegal in many jurisdictions, but not specifically stated in their privact policys and t&c's.

if its happening to you, i'd contact them just to be sure. Almost certain they would say its not mined for advertising purposes.