Good javascript frameworks toolkits compatible with mobile OSes?

I was recently hired to work on mobile Ajax applications. This is the first time I do this, as I always worked on usual 开发者_开发知识库Ajax sites on common web browsers. I'd need a framework and possibly a toolkit that works both on IPhone and Android... capable of abstracting the mobile browser the same way jQuery does with desktop browsers.

I've seen JQTOUCH, but it seems very much IPhone oriented. I'd like something more cross platform and lighter. Do you have any idea?

Check out Sencha Touch (new) and PhoneGap.

http://jquerymobile.com/ is also a good option that is cross platform (not necessarily lighter footprint than jqTouch though)