This just might affect you. If you bout a 3G iPhone in North America or Japan and got an "ultracompact" USB adapter, the results could be shocking--you.
It seems that some of the power adapters are faulty and the metal prongs can break and zap you. So, check with Apple, who will replace the adapters for free. Fixed versions are expected to be available on October 10.
In the meantime--stop using the adapter.