I've been investigating Android recenly, and have downloaded the SDK and had a play with it.
And in summary, I'm quite staggered at how poor the support is for audio in the Android SDK.
You can find-out more here.
The fundamental problem is that there is no way for a program to generate its own stream of audio. All audio resources must be from a URI of some sort, or from data bundled-in to the application, or from a file in the file system.
Of course, some bright spark out there might tell me that you can easily create your own "in-app" audio server with Java that you can access through a URI from that self-same application, and that can generate an audio stream on demand; I'd love to hear if this is the case!
On another note, the audio data capture system only allows you to send data to a file; there is no way for your application to get access to the audio as it arrives. So whichever way you look at it, there is no way to create audio FX boxes for Android.
This all reminds me very much of the JSR-135 multimedia APIs for Java, which were completely useless from the perspective of a low-level audio programmer.
I'm pleased to report however that if you want to create interesting audio apps for Mobile, then your needs are well served both by the iPhone/iPod SDK, and the Windows Mobile SDK. Shame about Android though!