The Droid Charge has compatibility issues with some or perhaps more than some bluetooth headsets/car kits/etc. I've spent quite a bit of time on the phone with Verizon tech support and even Samsung tech support. I've had 2 Plantronics Voyager Pro + headsets and 3 Samsung Droid Charge phones. Phone number two was a dud (probably been dropped or something) and would loose the pairing as soon as I turned the phone off. The other two phones and headsets all exhibited the same symptoms.
There is an occasional problem where callers can't hear you, but you can hear them. There is no way to know when of if the person you call can hear you unless they are actually on the phone at the same time. Imagine leaving a message for your wife saying you'll be home late, or for a client moving an appointment and all they hear is silence. These problems seem to grow until the phone disconnects itself from the headset. To get the phone & headset connected again, you have to delete the headset profile from the phone and go through the process to pair them again. This whole process repeats every week or two.
It is my understanding that other bluetooth headsets have similar problems connecting with the Charge. According to Verizon, they won't pursue a fix with Samsung unless they get enough complaints or see enough information in threads like this one. So if you have a problem like I do, please let us and Verizon know the details.
If you have a good headset that actually works properly with this phone, I'd like to know that too. I may need to buy another headset.