i didn't get much time to work on the plugin last week, but here's a WIP version attached if anyone wants to try it out.
Is there additional config that needs to be done for this? I installed and activated it in a test 1.0.3 instance, but my iPhone still displays the normal interface.
hm, no. it ought to just pick up right away. in a desktop browser, try loading up webmail - you should see it loading mobile.css as one of the network requests.
shrinking the browser down to be under 760px wide should trigger the CSS that displays the mobile view, as well.