If you were starting to build a relatively complex HTML5 app (for the iPad), what tools and frameworks would you look at using to make your life easier?
SproutCore looked like it might be useful if you could just use the front end UI on its own, but it has to be used with the Ruby server, which is no use to me.
Are there any libs like jQuery that simplify all the multitouch stuff?
Yeah, definitely. There's http://www.jqtouch.com/, which I've heard good things about.
I wouldn't bother going for anything geared towards mobile web development for the backend -- it's the frontend you've got to worry about. The rest is pretty standard. For completeness, I'd use the Zend Framework.
I know that this is an old thread, but i would just like to add that sproutcore is entirely backend agnostic. It is in no way tied to a ruby server or any other specific backend.
Also, Sproutcore has very good touch support. Check out http://blog.sproutcore.com/post/531215199/introducing-sproutcore-touch
For any late-comers to this question: jQuery Mobile is coming next month, and will include touch actions, though there aren't many details yet: http://forum.jquery.com/topic/touch-actions