neat find; I was wondering myself if they'd fit.
If you've got some lying around and want to use it as an alternative to the 150mah 1/3aaa batt available to save some money, that's great. But if you've already done the mod to get it to fit and have a few extra dollars, you can get a NIMH 1/3aa that has a 250mah capacity. That'd be the best reason for switching to 1/3aa IMHO. That'd be 5 times the original stock capacity but might add a little more weight.
You could use two of those for a dual-cell 1/3aa mod too.. it'd run longer than the 1/3aaa dual-cell mods, though you'd probably have to hack out all of the back window to get the second cell to fit, and you'd have to charge it for like 5 minutes