I've not tested this battery life at the moment, but I'm using the low voltage 168, the atmega168V, as the processor, so in theory a long time if drivers, software etc allow for it.
Current power options are, via USB FTDI cable, onboard CR123A battery (if battery holder is installed), or via external 3.3v source. The next revision board will probably have more power options, such as an on board LDO regulator for non 3.3v sources, i.e. lion/solar/wall warts and also a DC-DC boost regulator so it can be powered from a single AA for hand held applications.
The way I've designed the board is that you you can reconfigure power options via solder jumpers, so if you want to bypass LDO or DC/DC then solder or unsolder a jumper.
Jean-Claude over at http://jeelab.equi4.com/2009/05/14/power-consumption-baseline/comment-page-1/#comments has done some good testing with this RF unit and is reporting average power consumption of 3.4uA on his sensor applications, he is using the standard 168 and the RFM12 unit, so really the 168v should be less.
One of my interests is Wireless sensor networks so low power consumption and power source flexibility was high on my list of design requirements, currently the commercial motes available are just way too expensive for 'around the house' type of sensor nets, I know I could use the xbees, but these get too expensive when you want a few nodes around the place. I know these widget boards are not 802.15.4 compliant, so work needs to be done on a simple mesh, something that will fit in the 168 memory footprint, but they have the range and are low cost.
From my initial tests the range is great indoors, no packet drops at all around my house which is a reasonable size (well filled 800m square block), I've yet to do outdoors, but I would guess 100m - 150m no problem.
Once I've nailed down the current board revision which is just about complete, one of my next projects is a simple mesh network for these boards.
Currently jeelabs have drivers and a functioning network protocol that is fully compatible with these widget boards that allows for simple unicast with/without ACK and broadcasts which will suit most users.