I am aware of both Selenium and Watir, but neither seem to offer support for iOS and Android browsers (including touch gestures)
Is there anything out there that does? Any recommendations?
If there is no existing software, can anyone recommend a good approach for automated testing of mobile browsers (over and above JS unit tests)?
Documentation of the WebDriver says that Selenium (to-be Selenium 2.0) supports both Android and iOS, the real device and the simulator (though, obviously, you need a developer license to use it on a iOS physical device). From there on, it's just a matter of using Selenium 2.0 and writing tests for it.