The miniSWARM (Scalable Wireless Arduino Radio Module) is a new low-cost wireless Arduino development platform we're developing. We've crammed an ATmega128RFA1, USB connectivity, LiPo battery charger, chip antenna with a U.FL connector for an optional external antenna... all onto a USB stick-sized development board. It's fully Arduino compatible and we were able to dramatically drive the cost of wireless down by using the on-board 802.15.4 transceiver and the V-USB library for the bootloader/serial interface. On top of that we ported Atmel's new LightWeight Mesh stack to Arduino (more details in the Networking forum - http://arduino.cc/forum/index.php/topic,159324.0.html).
Please check out our campaign for more technical details and to see what the miniSWARM can do :-). Cheers!