Apple has launched a replacement program for the 1st generation iPod nano over the weekend. The website states:

"Apple has determined that, in very rare cases, the battery in the iPod nano (1st generation) may overheat and pose a safety risk. Affected iPod nanos were sold between September 2005 and December 2006.

This issue has been traced to a single battery supplier that produced batteries with a manufacturing defect. While the possibility of an incident is rare, the likelihood increases as the battery ages.

Apple recommends that you stop using your iPod nano (1st gen) and follow the process noted below to order a replacement unit, free of charge.

Note: This battery issue is specific to the iPod nano (1st gen) and does not affect any other iPod."