I received my first Jeenode yesterday, and this morning I have finished assembling it and a testing it with a Sparkfun FTDI board and USB cable. It appears to be working fine. I can upload and run the rf12demo program, and I can send data between the Jeenode and an Arduino Uno with the RFM12B board. I have also ordered a Jeelink, as that looks useful as a PC interface or for use with a Raspberry Pi.
I will now try some sensors attached to the Jeenode.
I also received two LightwaveRF magnetic switches. These work at 434MHz, so I should be able to detect signals from them with the Cool Components 434Mhz RF receiver. I will let you know how I get on.