In very rare cases, the two prong Apple AC wall plug adapters designed for use in Continental Europe, Australia, New Zealand, Korea, Argentina and Brazil may break and create a risk of electrical shock if touched.
Apple is aware of 12 incidents worldwide. The recalled adapters have either four or five characters or no characters on the inside slot where it attaches to the main Apple power adapter. More details on how to identify affected adapters are on Apple’s website. Apple’s other wall plug adapters, such as those designed for the United States, are not affected.
Consumers can exchange the defective plugs at any Apple store or authorized Apple service provider. Apple will also refund customers who may have already bought replacement plugs because of the issue.
[Update: on February 18, 2015 the Consumer Product Safety Commission officially announced details of the U.S. recall.