If you're still using a Thinkpad bought sometime between October 2010 and April 2011, best be aware that they're hot property right now - in the bad way. Lenovo's made a massive recall of Thinkpad batteries sold around that time due to them being fire hazards.
The laptops at risk are the Edge 11, 13 and 14 series; the T410, T420, T510 and W510 series; and the X100e, X120e, X200, X201 and X201s series.
To check if your battery pack is affected, look for a white sticker below the bar code on on the battery pack. The affected packs have one of the following part numbers: 42T4695, 42T4711, 42T4798, 42T4804, 42T4812, 42T4822, 42T4828, 42T4834, 42T4840 and 42T4890.
Unless you want a fiery incident to happen, take the CSPC's advice and remove the battery immediately. Replacement policies might differ depending on the terms of your purchase, so pick up that phone and call your friendly neighbourhood Lenovo service centre or authorised resellers.
The US Consumer Product Safety Commission (CSPC) first announced Lenovo's massive recall of these batteries last Thursday, with a full list of the battery packs and models affected. Over 34,500 laptop battery packs were recalled in the US, 2900 in Canada, and an astounding 115,000 in China.