After some research, here're are conclusions for the comparison:
PhoneGap and Titanium serve the same purpose: developing cross-platform mobile application.
However, they differ in several aspects:
Since the appearance of smart-phones, mobile development has been done in separate islands, with each island having it's own set of traditions and languages, "Objective-C", "Java", ".Net"......
So the demand for a cross platform technologies has increased, and indeed a solutions emerged, in this article I'm going to explore the main three technologies out there, "rhodes", "PhoneGap", "Titanium Appcelerator".
How it works?
So, this is the entry point for any technique targeting cross-platform, all of them are frameworks target the smart phone's web browser, but they differ in details, which we'll be discussing later.