Google have added voice-controlled searching to the T-Mobile G1, part of the new feature set introduced in the latest firmware update. The widget has been integrated into both the Android browser and the home screen search bar, in the form of a new microphone icon.
Tapping the icon brings up a "Speak now" prompt, at which point you can search for multi-word terms. If the app doesn't correctly recognize your voice, you can also choose the arrow to the right of the search box and see a drop-down list of other suggested interpretations. The Google Android team claim to be working on refining the recognition algorithms for future updates.
The functionality also works within the Android browser, and can be accessed by choosing Menu > Search and tapping the microphone icon. Unfortunately the new functionality is currently only available in the US, with the RC-33 firmware rolling out over this coming week. Have you tried voice-controlled searching on the G1? Impressed or disappointed?