ATUSB IEEE 802.15.4 USB Adapter
The ATUSB is an open hardware IEEE 802.15.4 USB Adapter.
It is based on the Atmel AT86RF231 transceiver and operates in the license-free 2.4 GHz band using the IEEE 802.15.4 physical and link layer. Note that IEEE 802.15.4 is different from IEEE 802.11 (WLAN) and IEEE 802.15.1 (Bluetooth).
atusb can communicate at the physical and link layer with any device that implements the IEEE 802.15.4-2006 standard for the 2.4 GHz band. They are fully supported by the Linux kernel WPAN project (see linux-wpan).
For more information on atusb please see the atusb open hardware project homepage
A PDF Rendering of the Schematics is available from here