Are there regulations or adverse effects regarding Bluetooth in the cockpit? Are there any FAA regulations concerning wireless Bluetooth headsets in the cockpit of any aircraft? Moreover, I'm interested in finding out if the Bluetooth protocol (IEEE 802.15.1) will adversely affect any aircraft avionics in terms of radio interference or other Electromagnetic Interference (EMI). If anyone has any experience with this, thoughts and comments would be greatly appreciated.
There are multiple aviation headsets approved by the FAA that have built-in Bluetooth.  

Based on that, I'm going to say that this has been tested and will not interfere with the aircraft avionics.  Radio/EMI testing is part of the testing that any device approved by the FAA for use in an airplane must go through.