I'm on a Mac and I've been working on this app for about three weeks now. Today I launch Titanium and go to my app, only to find that the Android option is now missing for my app. It was there before. It's there for the other projects I have in Titanium. Why is it not there now?
I searched for this error and found people saying to replace android.py. While it didn't sound exactly like my problem I did that. It didn't make a difference.
Make sure you're using mobilesdk 1.3.0 or greater. If it's still missing, the build/android folder may have been deleted. You might need to create a new project and just copy the resources over to have it regenerated.