A subset of the rechargeable batteries sold with Nikon cameras is being recalled. Nikon has put out an advisory that certain lots of its Model EN-EL15 lithium-ion batteries can short-circuit, causing the outside to deform from overheating and possibly posing a hazard to anyone who handles it. The batteries in question were sold starting in March 2012, either alone or with a Nikon D800, D800E, D7000, or Nikon 1 V1 advanced camera. So far, there have been seven confirmed reports worldwide, and Nikon is offering to replace anyone with one of the affected batteries.
If you happen to have an EN-EL15, Nikon recommends you check the ninth digit on the lot number (it's the one marked in red above.) Only lots marked with either "E" or "F" are affected; you can find a return form or toll-free number to return the battery here. Until you've returned it, you'll want to remove the battery from your camera. We don't envy anyone with one of the effected lots, but it looks like Nikon at least caught the problem a lot earlier than we've seen in some other recalls. Possibly because the problem is limited to two lots, Nikon hasn't pulled the batteries from stores, so even new purchases might match the description above.