Amarino doesn't use serial. It's using Bluetooth -- which is an interesting solution. I'm researching doing a cheaper Bluetooth implementation, which would help work around communication between Android and a lot of other devices (think MIDI). Most people now are using the BlueSMIRF, but that thing is about four times as expensive as it should be. We just need a cheap, DIY Bluetooth board you can tag to anything.
That said, I'm likewise interested in serial. The iOS dev crowd have an interesting solution. They're augmenting OSC over wifi with OSC over UDP *over serial*, because via the USB tethering solutions you get a network connection. It sounds as though you then run into some other security issues, so we'll have to see how 2.2 handles tethering on Android. But that could wind up being our solution - no hacking or custom kernels required.
I have tested the above serial solution with the hacked kernel, though, and can confirm it definitely works. We even got as far as hooking up an Arduino MEGA and doing a custom MIDI interface, thanks to Wesen (of
http://ruinwesen.com/)
