I really like the plug-in but something in the CSS seems to be messing up the admin edit page for posts and page editing (.../wp-admin/post.php?...)
On the admin/edit pages - and only those pages - my website background image (body.jpg) shows up, and the insert media links are all messed up. All other admin pages seem to be fine.
Everything goes right back to normal when I deactivate MapPress.
I'm on WP 3.0.3.