Google Voice Search app for Android-powered device is upgraded with voice recognition support, according Google's announcement today. So for Android 2.2 or higher owner, you can activate the app so Google can activate a speech model for your voice in order to increase the accuracy of the app over time.
Unfortunately this app can be used in United States and supports only English language only. But don't worry the Mountain View company promises they will make Voice recognition to support other language and countries in the future.
Only Android 2.2 or newer can uses voice recognition