I'm running a child theme for P2 version 1.2.1.
I've just upgraded the site to WordPress 3.1-RC2 and can no longer update the individual template files via the built in editor.
When I select the parent theme, P2, all my files are available for editing. But when I select the child theme, simplechurchipedia, the only file listed and available for editing is the style sheet.
Hopefully that's not a "feature" of the new version as that would be a HUGE pain in the rear - especially now that I've adopted child themes for almost all my sites now.