I know I am a bore about this but I would seriouswly weigh up the value of a very small size camera versus one that takes AA style batteries. Generally the proprietry batteries you get in very small cameras do not hold a very high charge (measured in MaH)and do tend to degrade as they get older. Rechargeable AA style batteries now go up to 2500MaH and, even if are caught out without spares, you can always get alkaline batts in an emergency. My last (and only) camera with a proprietry battery would last well less than a day on one charge whereas I can now go for many snaphappy days without changing.
Also be carefull about claims that Lithium Ion batteries do not have any memory effect solve all these problems. For Digital Cameras, that draw very high power, this is not true.