I used Bluetooth for the first time today, to Hotsync my Palm Tungsten T with my laptop using a D-Link DBT-120 USB Bluetooth adapter. Pretty spiffy, and not much slower than standard USB synchronization.
Update (2003-01-30):
I have also synchronized my new SonyEricsson T68i Bluetooth-enabled cell phone with Outlook, as well as with iSync on my iMac G4. The process is painfully slow (probably due to sluggish software), but the end result is pretty cool. It seems Bluetooth is where USB was in 1995, i.e. barely functional drivers and not that reliable (my Sony phone has a tendency to unpair itself from my Tungsten T or my PC), but it has potential. You will just have to wait a couple of years until driver support migrates deep into the OS (unless you use a Mac, of course).