I updated from 10.4 to 10.4.1 a couple days back and today when I went to transfer some files from my Nokia 6680 to my laptop I got a pretty opaque "Sending Failed" error. After a little bit of debugging (sending to and from other devices, receiving files on the phone) I decided it must be the powerbook at fault and started googling for answers, only to stumble across this LiveJournal post detailing the same problem and his workaround.
With the info in his post I went to work on my preference files with hammers and tongs, it seems in the com.apple.Bluetooth.plist file, when you change the Directory it only changes the PIM directory, not the 'Other' directory leading to the problem. Here's how to fix it:
defaults write com.apple.Bluetooth OBEXOtherDataSaveToLocation \defaults read com.apple.Bluetooth OBEXPIMDataSaveToLocation\\What this does is grabs the value from OBEXPIMDataSaveToLocation, the location you set in the Bluetooth preference pane, and sets it as the value for OBEXOtherDataSaveToLocation, the location that gets stuck at ~/Documents. Hopefully Apple can do a small fix to update this.