Forgive me for just not understanding at all, but where do we do our actual coding? I was assuming there would be an IDE or something but it doesn't appear that way at all.
when you create a project in Ti Dev it creates some files and folders in the directory you entered. The main file you need to look for is app.js this is the file that runs on the app start up and links everything together.
i would also recommend checking out the getting started guide http://developer.appcelerator.com/doc/mobile/get_started
should clear a few things up for you :)
Titanium is just the man in the middle. Your coding will be done in the IDE of your choice. Could be Notepad++, dreamweaver or whatever you like.
The system intentionally does not provide an IDE - instead letting you use the editor and environment of your choice.
This has its ups and downs - it certainly makes it easier than trying to learn (yet another) IDE. But I haven't yet found a good way to get my IDE of choice (Eclipse) to help me out with the syntax and contents of the Ti hierarchy, and one of these decades I'd like to do the compile/launch from within my IDE instead of having to keep the Ti application running to do the compiling.