What I exactly need is to load and show images from a location external to the application's. As the photos are constantly changing my proposal was to load them from the Camera Directory so that it's as simply as storing in that folder the images.
The specific need here is: How can I load and show on an img tag element an image from the camera directory?
Raymond Camden has very good tutorials on some basic uses and some cool features that a developer can use with PhoneGap. In your case, he has a tutorial that semi-relates to you question. He gives the sourcecode with the tutorial so I'm sure you'll be able to extrapolate from there. Basically it's a little Diary app that you can add a picture to. I'm sure you'll be interested in the picture part of the app.