Well, after all that, if you're still thinking of making a native app, I salute you. I admire your spirit and wish you the best of luck.
Note
If you Google "jquery mobile phonegap performance", you're going to find a lot of negative articles. The problems seem legion. Sluggish performance, screen blinking between transitions, and so on. Not that Sencha Touch or any other mobile web frameworks seem to be doing any better. Just be aware that it may not perform as well as it would over the web.
PhoneGap started out as a project to take regular HTML, JS, and CSS and package them nicely into a distributable app for any app store. Eventually, it became part of the Apache Software Foundation. At its core, PhoneGap is Apache Cordova. In fact, if you go the documentation site for Cordova, it's actually still hosted at http://docs.phonegap.com/.
In addition to simply compiling down your app, you also get access to the following device-level APIs.:
Accelerometer: Tap into...