To my knowledge (no such device owned), on Android 3+ devices a page like http://openlayers.org/dev/examples/mobile.html will work straight out-of-the-box when opened in the stock browser. As mentioned, since OL 2.11 mobile device multitouch events are supported, they have also provided a jquery mobile & geolocation demo which works great on android.
For the majority of android 2.x devices, you will need to deliver your own webview container including a polyfill such as WMP if you want spread & pinch zooming to work.
Otherwise you're only left with using the zoom buttons - which is not always preferable given the small size of many touch screens.