Bluetooth is curently crippled for most comps (mine is MacBP), by apple or att, for the 3gs in this country. They don't want you to tether your phone and browse and whatever. You will probably find that your laptop or desktop will see your phone and vice-versa. It would be extremely useful for file transfers on a jb phone to use a simple bluetooth connect. Att told me that they are considering a "plan" (10-20 bucks) which will allow us to use bluetooth.
Of course, if you have already jb your phone, dig a little further and you will find IPSW break that will allow you to do what you want.
Sum: you (and me) ain't getting bluetooth on the up-and-up.
Call att if you are incredulous. I say this with the knowledge that att can tell when you are using bluetooth, and they pass that to apple for torrent addicts, and for "legit" folks who just want to use a full size keyboard. Anyone correct me if I am wrong.
Luck,
DC
p.s. if you are only looking to transfer downloads from your phone, just make an ad-hoc network and go to town. That is what I do.
I am drunk and just reread your post. Disregard. Sorry.