I am also curious what the limitations for (e.g. Phone Gap Apps) are..
You can find the list of apps which is developed by Phone Gap.
Even though cross mobile platforms like Phone Gap giving lots of plug in's to make use of native components like camera and GPS etc., Still if you want to make use of full phone specific usages / hack ( for enterprise apps we are allowed to do hack if it is iOS apps ) and for better performance.
Don't forgot that Facebook also recently killed its hybrid app and moved to native.
We recently made public PhoneGap-built Intone, an app to discover and read quotations from the Baha'i Writings.
PhoneGap allowed us to build iOS and Android version simultaneously. Great upside was that though I have no knowledge of Objective-C, but as a designer was able to tinker with the CSS to finetune details. It plugs into the ambient light sensor too.
Limitation is that it doesn't quite feel native. It's missing a certain smoothness on older phones and some native interactions are very hard to replicate in JS.