Xbee > Telos? Cost, yes.
The cost of the Arduino Xbee shield is out of control. For that price alone I can get a complete solution from moteiv or crossbow. I’d love to make the arduino a WSN platform but we really need to cut the price down so the entire solution (arduino+xbee) is more like $60 bucks. If anyone wants to think about this give me a shout, I’m willing to help where I can.