I needed the same 'live camera view' for my augmented reality (AR) application. Phonegap does indeed not offer a live camera view yet. Therefore, I am using a Wikitude plugin for Phonegap.
Although Wikitude is an AR SDK, the basic functionality it offers is that exact camera live view.
How it works? You define a 'world', which is a basic HTML page. Once loaded, the background of this webpage will be your camera live view. In this webpage, you can still run PhoneGap Javascript code. You can call this 'world' whenever you want from your PhoneGap code.
Where to start You can get the PhoneGap plugin from https://github.com/Wikitude/wikitude-phonegap. Setup instructions and example projects are included. There is an unlimited trial of the Wikitude SDK available, you will need that as well.