When fastdev is enabled, emulators for 4.1, 4.2, or 4.3 Android SDK will crash. This is potentially a side effect of a pull request (4474).
1) Create a new project using a 3.1.2 SDK post pull 4474 (after July 23rd)
2) Launch in 4.1 or later emulator (4.1 - 4.3 currently)
If on appcelerator Studio, your emulator will hang. If on Titanium studio, your emulator will crash
No crash, the emulator functions as expected.