Hi.
I've implemented USB Support (both FTDI-based Duemilanoves and ATMega-based Unos) for my app but it's not tested:
https://play.google.com/store/apps/details?id=name.antonsmirnov.android.arduinocommander
If you are interested in testing, please write me to dev at antonsmirnov dot name
and i will send you apk and testing tutorial. Thanks!
PS. It's free app and free feature