aprsdroid is pretty nice. I've used it to test messaging when I'm RF only, and I've gated messages to the internet from my phone using the speaker and an HT. Glad to have it. :)
I didn't know it was written in scala, though. That adds extra awesome to it.
This is the spirit that made HAM Radio a success in the first place. I wish more of it would be still present.
Out of the same motivation, I have developed an open source APRS app for Android (http://aprsdroid.org/) written in Scala. It is available (for a fee) on the Market as well, but you can download the APK freely from the home page. :)