They want to know my address, my tastes, my shopping habits, etc. They have huge databases correlating my information against everybody else's and extracting business models and marketing strategies out of that. Not only that. It would correlate information from my Palm device, my cell phone, my TV, and even from my microwave oven. It would store and combine this information and give me feedback on things that I'm interested in.
Interoperability is the keyword here.
Bluetooth devices would allow me to rate the movie I just saw and exchange that information with other people in the same theater. And if someone thinks the same as I do, it will offer to exchange other movie ratings of mine with other devices. Then it will try and find a match and will be able to better determine if I would like some other movie or not. It would be the first effective insanely great real Personal Assistant. It would prevent me from buying that useless item at eBay, because it knows how much I would regret it later.