Ubertooth One is an open source 2.4 GHz wireless development platform suitable for Bluetooth experimentation. Commercial Bluetooth monitoring equipment can be found for over $10,000. Project Ubertooth seeks to produce an affordable platform that can be used for Bluetooth monitoring and for the development of new Bluetooth and wireless technologies.
Visit Project Ubertooth for information, open source design files, and documentation. The latest firmware (Ubertooth Release 2014-02-R2 at time of writing) can be also found on the Project Ubertooth page.