I stopped by the Windows Phone/PhoneGap/Cordova hackathon on Monday and spent some time working on WinPhone support.
git master for the Wikipedia mobile app now builds and mostly runs on Windows Phone 7.5 'Mango' (tested in emulator). The current styles aren't compatible with the IE9 web engine so it doesn't look great, but since we intend to do a major style change soon there's no rush in fixing that.
Some gotchas discovered during previous and current attempts at making it work:
* You have to tweak jQuery's AJAX settings to make cross-domain requests work
* local files must be AJAX-loaded with a full URL (eg message files, sitematrix.json)
* as a weird hack, ask for 'text' and get JSON when loading sitematrix.json (say whaaaaaaat)
IE9 doesn't support CSS gradients, and I'm not sure about multiple backgrounds, so the header bars and buttons display incorrectly.
It's also currently rocking the iOS-style toolbar, which should be replaced with a more native Metro-themed AppBar in the future.
Some system integration still needs to be added:
* opening external links in Internet Explorer instead of in the app
* (potential) live tile updates -> stick today's featured article on the app tile etc
I don't think there's a good way to hook into the global search, which is unfortunate -- that's one of the things I like on Windows 8's Metro/tablet interface.
We've also got a great community-sourced fork of an earlier version of the app that has tried to do more of the system integration, so that should give us good inspiration on how to get more of those going in the current version.