What are the advantages and disadvantages of using Phonegap and Titanium?

I am planning to create a cross platform application which works in Android, iPhone and Blackberry? I thought of using Phonegap or Titanium. My questions are as these:

Whether in cross platform if it is possible to achieve all the native behavior of all phone models, something like in Android menu and iPhone gestures?
Apart from cross-platform advantage, what are other advantage do it have?
What are the disadvantages? Is there any limitation when it comes to comparing to native app?
Whether I can use same code without any modification in all the devices or i have to change the code with respective to device identified dynamically?

Solution

Previous discussion on Stackoverflow: Comparison between Corona, Phonegap, Titanium

A good clear explanation from Jonathan Stark: http://jonathanstark.com/blog/2010/04/05/phonegap-vs-titanium-mobile-et-al/

In terms of your questions:

To check which native features are available for each framework you will need to check the API docs of each of the frameworks: The phonegap ones are here http://docs.phonegap.com/

The advantages/disadvantages I think are covered in the two links above.

It will depend what you are doing but I imagine you will have some differences in your code for each platform.

Hope that helps!