I use this adapter too - GC-WB300D. It came with my mobo. There's no driver for wi-fi yet, but the bluetooth module does work with ML 10.8.2. flawlessly ! I've got Apple's bluetooth magic mouse and keyboard.
The only thing is: unfortunately you have to boot to Windows ( or Linux ) first so that the adapter is "turned on". If you boot to ML first ( "cold boot" ), it won't work !
Somebody said in another forum that this bluetooth adapter lacks memory for firmware so, everytime you turn your PC on, the driver uploads firmware and then the OS recognizes it. The MAC driver don't do this, so ... it's not "turned on".
Would appreciate If anybody could clear this out.
My Build: Gigabyte GA-Z77X-UDH5 Wi-Fi F14 // i5-3570K // ECS GTX460 Black Series // 8 GB ( 2x 4GB ) Patriot DDR3 G2 Series 1600 MHz