PhoneGap influences web technologies to work with native device features such as Geo Location, Accelerometers, Sound, Vibration, Contact support and many more. It wraps the web view with container, this container gives the view access to API available on the device that may not be available on the web view alone.
There are few disadvantages with PhoneGap as it still may have bugs somewhere and libraries, documentation is still a hunting task for the geek. It’s sometime unsuitable for graphic intensive application.
It has a more liberal license (MIT vs Apache open source license), Easier testing in browser or simulator created in Adobe Air, supporting more mobile platforms.