No doubt everyone knows about this by now BUT although there is a list of phones which came out with the battery being recalled, through upgrading you may have one or two of these batteries floating around and being used as a spare.

You can still get them replaced and by going to the nokia website you can find out if that is correct.
This recall appears to be the subject of conjecture, assumptions and half truths, if you have a BL-5C battery check it out on the nokia site regardless of what model Nokia phone you have. I discovered I have 2 of them.

cheers

Jo