Developers should take heed of the "uncanny valley" point Andrew makes. While I come across the rare example of an app that pulls off stock UI via CSS well [1], most fail somewhere along their approach and end up subtly repelling the user.

I wrote a PhoneGap app [2] and this fact was among my considerations when designing it.

The performance points are spot on with my experiences, especially avoiding any height and width manipulations. Most of the height transitions in my app are actually translations on the Y axis, preventing reflows. Rather than completely rely on the browser's native layout capabilities, it can pay off tremendously to do some of those calculations and translations manually.

[1] - http://cheeaun.github.com/hackerweb

[2] - http://chaincalapp.com

Important topic. Here is an in depth look at touch vs click, how to sprite images, etc http://maxogden.com/fast-webview-applications.html

Also I think local data and avoiding network round trips is key to reliable consistent high performance. This is why we built Couchbase Lite for mobile. https://github.com/couchbase/couchbase-lite-ios

Ugh, instead of dealing with all the edge cases and learning THEIR api, just learn OBJ-C and Cocoa instead.

"So wait, you are telling me, I can build native mobile apps with just css and js"

-"Yes, all you need to do is learn these 1000 quirks and edge cases for performance, and learn/memorise our API"

If you are targeting multiple platforms, that's not always an option. PhoneGap gives you the option to target 10 platforms w/ an HTML/JS codebase. Native will always yield better performance and have best access to device APIs, but will also be more expensive to develop & maintain. PhoneGap gives broader reach at lower cost.

10 target platforms is not a good argument. Only Android and iOS are relevant. Really.

Speaking from experience, developing apps with webview on mobile is a minefield. Combining that with jQuery-mobile is akin to throwing a sheep into that minefield.