I've been syncing my Palm Tungsten and phone via Blue Tooth (BT) for months with never a hitch until this morning. I kept getting an error from my Palm that the port was in use by another application. That happens sometimes and I've found that one of three things will fix it. First, turn off syncing (in the HotSync application) and turn it back on. Second, unplug and replug the BT dongle. Third, do a soft reset of the Palm.
None of that worked this morning. I verified that the Palm and BT dongle worked by moving to another computer. I tried configuring BT using another account on my iBook. I tried throwing away the BT prefs. I ever restarted the iBook. Then, and only then, did I think to check out the BT menu widget. It thought there was no BT connected.
On a couple of ocassions I've run into problems that were solved by turning the computer off all together. That's what I did - and BT once again worked. I guess this isn't so much as OS X tip as it is a cautionary tail. When all else fails turn off the machine. A restart isn't a cold start.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20030530095130891