jQuery in Action, good book about jQuery
In addition there are a number of great blog posts and libraries helping to develop native-looking web applications for the iPhone:
Universal iPhone UI library, many nice CSS tricks
And a number of performance related posts from Google (from the Gmail team that developed the excellent Gmail mobile application):
Because eventually I want to add automatic data synchronization support to our DSL, I’m also looking into synchronization strategies. I found a nice post about that. Of course, Apple’s own iPhone web app documentation is also very useful.