If you are targetting iOS 6.0 or later, you don't need iWebInspector as the new version includes an official Web Inspector. More info here.
It works for any web in Safari -the web browser-, for a chrome-less webapp (full-screen) and also for apps using UIWebView -including PhoneGap applications-.
The Remote Web Inspector is part of the open-source WebKit project and is included in iOS5 by Apple. This tool is inspired on the discovery made by Nathan de Vries on how to enable the Remote inspector on iOS 5.