The follow links have useful information about Bluetooth for multi-robots.
http://lejos.sourceforge.net/forum/viewtopic.php?t=1964&start=15
http://lejos.sourceforge.net/forum/viewtopic.php?t=1785
http://lejos.sourceforge.net/forum/viewtopic.php?t=439
http://pirate.shu.edu/~wachsmut/Teaching/CSAS-Robotics/Lectures/12-BTCommunication.doc
http://www.juanantonio.info/p_articles/archive/2008/LEJOS-BLUETOOTH.pdf
http://lejos.sourceforge.net/nxt/nxj/tutorial/Communications/Communications.htm