I'm trying to create an asynchronous multiplayer iPhone/Android game in which players find each other through facebook, twitter, random query, or username challenge (think Words with Friends' session options) and simply upload short sound clips for their turn. Other players (excluding the uploaders) can see "completed" sessions (sessions where both players have uploaded a sound clip) and vote on a winner after hearing both sound clips. Simple.

My actual question is where would a solo developer start on a project like this? I'm new to mobile development, but I have several years of programming/scripting experience and I pick up new languages and programming concepts really quickly, especially when I have an open source that's already similar to what I'm aiming for to dissect, learn from, and tweak. Is there an ideal dev app to use for this specific type of game? An ideal language to write it in?

Android has special features built in for social sharing and networking. It is very likely you will find some construct that can help you... in its massive library. You're better pick Android only and focus on it for the time being, the barrier to entry is much lower. Be careful of allowing user content, they will grow the storage requirements of your server massively... and can be sold as premium service so... good idea.

For Android you have Java being the official choice, C# through Xamarin or C++... In my experience the Java based framework is quite painful for networking but unless you have some serious performance requirement I'd go with it anyway.

Thanks that's a start. I have at least beginner-level Java experience. I've also read that it plays nicely when venturing into cross-platform