Hi there,
I have the same problem with my mid-2011 iMac.
I tried all the above mentioned steps - nothing helps.
This is my console log (search string "bluetooth") after booting:
27.07.12 15:18:06,000 kernel[0]: IOBluetoothUSBDFU::probe
27.07.12 15:18:06,000 kernel[0]: IOBluetoothUSBDFU::probe ProductID - 0x8215 FirmwareVersion - 0x0191
27.07.12 15:18:06,000 kernel[0]: IOBluetoothUSBDFU::start
27.07.12 15:18:07,000 kernel[0]: [IOBluetoothHCIController][start] -- completed
27.07.12 15:18:08,095 IOBluetoothUSBDFUTool[81]: 4.0.9f8, Copyright © 2002-2012 Apple Inc. All rights reserved.
27.07.12 15:18:08,095 IOBluetoothUSBDFUTool[81]: IORegistry idProduct 0x8215
27.07.12 15:18:08,218 IOBluetoothUSBDFUTool[81]: switch to DFU mode
27.07.12 15:18:09,000 kernel[0]: IOBluetoothUSBDFU::probe
27.07.12 15:18:09,000 kernel[0]: IOBluetoothUSBDFU::probe ProductID - 0x8215 FirmwareVersion - 0x0191
27.07.12 15:18:09,000 kernel[0]: IOBluetoothUSBDFU::start
27.07.12 15:18:09,219 IOBluetoothUSBDFUTool[81]: IORegistry idProduct 0x8215
27.07.12 15:18:09,311 IOBluetoothUSBDFUTool[81]: CFPreferences idProduct 0x8215
27.07.12 15:18:09,311 IOBluetoothUSBDFUTool[81]: BoardIDTable idProduct 0x8215
27.07.12 15:18:09,311 IOBluetoothUSBDFUTool[81]: filename /System/Library/Extensions/IOBluetoothFamily.kext/Contents/PlugIns/IOBluetoothU SBDFU.kext/Contents/Resources/2046_8215.dfu
27.07.12 15:18:09,311 IOBluetoothUSBDFUTool[81]: DFUFileSuffix 0x0201 0x8215 0x05AC 0x0100 0x554644 0x10 0xA05078FB
27.07.12 15:18:14,987 IOBluetoothUSBDFUTool[81]: Could not USB DFU get status for device 0x7fd6c1c0e320 with error 0xE0004051
27.07.12 15:19:15,033 com.apple.launchd[1]: (com.apple.IOBluetoothUSBDFU[81]) Exited with code: 1
Maybe this information could bring up a possible solution?
Thanks, Niklas
(x-post)