The iPhone Supports Talk-Thru in BluePhoneElite
Talk-Thru turns your Mac into a Bluetooth hands-free device. BluePhoneElite 2.0 lets a Mac answer the iPhone and uses the Mac's mic and speakers for the conversation.
Just another application I recently tried that utilizes the iPhone's bluetooth functionality.
It will be nice when Apple adds additional profiles to take advantage of more of the apps features. This goes for Salling Clicker too.