I remember from the early days of Titanium there was a specific "Mobile development guide" document (it may have been called something different) that walked through the various UI components and offered guidelines for how to create iPhone apps. I believe there was a similar doc for Android, although I didn't look at that at the time.
I can't seem to find this document. I recall it was quite prominent on the site, almost the first thing you'd find, but now it doesn't seem to be anywhere.
So: where can I find this doc, or if it no longer exists, what document is now recommended for understanding the various UI elements and APIs (outside of the API reference)?