Apple is recalling the adapters sold on the 3G - the reason should be (from Venturebeat)

The reason for the recall is that there is a risk of electric shock if the adapter’s metal prongs break off in power outlets. Because of the shape of the adapter, this has occured in a “very small percentage” of adapters sold, according to Apple. No injuries have been reported.

If you go directly to the source at Apple you can find out a few interesting things…

#1 Apple doesn’t call it a “Recall” but an Exchange Program

Today Apple announced the Apple Ultracompact USB Power Adapter Exchange program.

#2 The Exchange Program mainly affects the far west and east:

1. US
2. Japan
3. Canada
4. Mexico
5. Several Latin American countries (click here for a detailed list of countries)

#3 Apple really does care!

Customer safety is always Apple’s top priority, and therefore we have voluntarily decided to exchange every ultracompact power adapter for a new, redesigned adapter, free of charge.

Users with ultracompact power adapters should immediately stop using them until they exchange them for a new, redesigned ultracompact adapter.

See Apple Sources Here.