Someone asked in a Photography magazine:
"if i store my dslr battery in the camera, will it run down"
and the answer was:
There's an ikhtelaf (difference of opinion) between camera makers. Batteries run down in some cameras, but in the others it doesn't. So recommended solution is to remove the batteries if you are storing it for more than two weeks. But try it out, and experiment
Most photographers carry a number of batteries with them, including spares. An organizer would definitely help. Here's one - just an example.