Google has added voice search to the Android platform via the new software update.

Because it was trained on Goog411 (which is currently only available in the US and Canada) Google voice search has difficulty with other accents. Here's a statement from Google explaining why:

The acoustic model for Voice Search was trained, in part, by using data from GOOG-411 which has only launched broadly in the US. Since the acoustic model was trained using mostly American accents, the tool currently works best when receiving queries with American accents. While you can still download the Google Mobile App and turn on the Voice Search here, we've turned off the voice functionality by default when the app is downloaded from anywhere outside of the US. We don't have any specific launches to announce at this time, but we think this is exciting new technology and the speech recognition and understanding will only get better for other accents and jargon as we keep working on it