StumbleUpon officially released a native application for both Android and iPhone. Before you are able to use the app, you must sign in or register. The app consists of a built-in browser with bars on the top and the bottom, which cannot be hidden. The top bar has the thumbs up/thumbs down and the StumbleUpon button. It also allows sharing with other social networks, such as facebook and twitter.
The application is currently in the Market. Download today and give me any first impressions you may have!