If your iPod Nano has been getting hot, really hot, you might be in for a free replacement. Apple recently acknowledged that in rare cases, the iPod Nano battery (first gen) can overheat -- so much so that it poses a safety risk to its users. The defective models were sold between September 2005 to December 2006.
Here's the warning message from Apple:
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.
If you think you are eligible, start on this page and fill out your info. Apple says you should get a brand spankin' new replacement within six weeks. The replacements will not be personalized and you should be sure to back up all your data before sending in the overheating Nano.