According to Harmon (the manufacture of the Infotainment system) the currently supported Bluetooth profiles in the firmware are:
HFP
A2DP
AVRCP
MAP
HFP is hands-free profile; this is for interfacing a cell phone to a hands-free kit in a vehicle.
A2DP is advanced audio distribution profile; this is for streaming audio between a media device and a (vehicle) radio.
AVRCP is for remote control of the radio/media player; it allows a remote device to pause, skip, fast-forward, etc. on music tracks.
MAP is message access profile; it's used to exchange messaging data between a cell phone and a radio. This is typically used in vehicle systems for displaying (or speech to text if supported by software) of SMS messages.
What was NOT listed in the specification was HSP-headset profile. This is why your Bluetooth headset won't work with the 6.5 infotainment system.
As many people with recently manufactured cars have discovered, like Ford Sync users, if you're on speaker phone in your car and you turn your headset on (HFP), the headset (HFP) will grab control the phone from the car. The same thing happens with the new HD audio system with the current firmware.
The only ray of hope Bluetooth headset users have at this point is that there could be a firmware update in the future that adds additional profiles (like HSP).
Harmon will have to write a future firmware update for the use of a Bluetooth Headset.