Apple on Tuesday released a 1.5 MB “Bluetooth Firmware Update for Mac OS X 10.4.3.” Apple’s page reports that the update (1.2) “improves Bluetooth performance and reliability issues.” At the time of this posting, the update is not available via Software Update.

The Bluetooth Firmware Updater supports D-Link USB Adapters and Apple internal Bluetooth modules for: iMac G4, 12" and 15" Powerbook, iMac G5, and Mac Mini.

Sources: AppleInsider | Apple released Bluetooth Firmware Update, Bluetooth Firmware Update for Mac OS X 10.4.3 – Apple

UPDATE: Odd, the updater told me that an update is not needed for my computer.  Checking in ApplicationsUtilitiesBluetooth Firmware Updater, I found that I already had v1.2.0 (1.2.0f6).