What is PhoneGap?
I just explained PhoneGap to a client wanting an iPhone app. I thought the explanation was good enough to share. If you're trying to wrap your head around it, I hope this helps...
PhoneGap lets developers use web technologies to develop an iPhone app. Apple has a web browser object developers can use to display HTML content. Usually developers use it to display HTML from a remote web server. What PhoneGap does is let developers create their user interface using HTML in the web browser object instead of the built-in user interface objects (buttons, lists, text fields, etc).