My first question wold be whether or not you need the jQuery at all. As I understand it (but that's not saying much) to use the mobile version you also need the main version, which means a big download. Not sure if that's true, though … (I need to find out).
It does seem that a trend is starting to make one website that responds to different devices. People acknowledge that this may not suit every site (such as the really big ones) but it's a general principle worth keeping in mind.
So using media queries etc is a good way to go. There's a really interesting slideshow that takes this issue even further, which is worth a look:
Rethinking the Mobile Web by Yiibu
Basically, the idea is that you start with a plain, vanilla stylesheet that will serve any device, and than layer nicer styles over the top of that with media queries for devices that understand those. It kind of reverses the thinking process, and is a fairly compelling approach, I find.