The jQuery Mobile team has announced the release of Alpha 4 version which supports Windows Phone 7. Here is their announcement from their blog post,
We’re thrilled to announce WP7 is now a supported platform and has a solid A- experience. All core features work great on both WP7 and desktop versions of IE 7 (8 & 9 are close, but not perfect). Keep in mind that WP7?s browser is fairly close to IE7 so advanced CSS features like rounded corners and drop shadows aren’t supported but the layouts and widgets all look great within the capabilities of the browser. We’ve added a polyfill to bring pseudo-media query support to this platform, which we plan to improve with a native media query interpretation at a later stage. We also plan to support the future upgrade to an IE9-based rendering engine on WP7 later this year.