Apparently with Android 2.3.4 and 3.1 one can now access USB accessories.
I have a Ardupilot Mega (based on Arduino) board with a USB cable connected to my laptop, a
http://slickdevlabs.com/
I am currently using the library in my own app, however I think you can get away with just the app that slick has on the market. There are two free apps and one is the "pro" version of one of the free ones; search slick usb in Google Play.
It does use HOST mode and you can change the baud rate to whatever you need.