Apple today announced a voluntary recall program for AC wall plug adapters and Apple World Travel Adapter Kits. For now, this program is limited to adapters sold in Hong Kong, Singapore and the United Kingdom. Apple is doing this because the affected three-prong wall plug adapters may break and create a risk of electrical shock if touched. Apple mentioned that six such incidents happened worldwide.
These adapters were shipped with Mac and certain iOS devices between 2003 and 2010. It is important to note that this recall program does not affect any Apple USB power adapters.
Affected customers can exchange their adapters, more details of this program can be found here.