It seems MobilePress suddenly stopped working on my blog today at http://www.marcschultz.com/blog
The only recent change I have made was to put in a plugin for a widget for following my blog on social media sites.
The plugin I added is called: "Follow us on widget"
http://vijayakumar.org/web-development/easy-follow-us-on-wordpress-widget-plugin/
I don't think this should cause any conflicts with MobilePress, but not sure.