jQTouch is app-like functionality you can run in the iPhone web browser. (maybe some Android browsers too?). It has some cool things for adding the app to the home screen and etc. Much different focus than jQuery Mobile.
jQuery Mobile isn't targeted at "app like" functionality (like Sencha/jQTouch) as much as it is an underlying set of things you need to develop mobile friendly websites and web apps. jQuery Mobile has a PJAX navigation layer, touch friendly inputs and layout and design framework. It is meant to take web content and give it the widest range of distribution at its core.
The project is gearing towards 1.0… so I'd imagine they'd be clearing the marketing stuff up soon so people recognize the project's strengths easier.
Until then, you can come to my presentation and find out. =)
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Marc Grabanski
MJG International