I've been using Theme Check and it's a very useful bit of kit. Our first theme should be ready for submission soon!
Instead of "one or more errors", why not display the number of bits of feedback? This way we can track progress of the number that we're fixing :)
RECOMMENDED: Text domain problems in index.php. The twentyten text domain is being used!
Line 38: <h1 class='entry-title'><?php _e( 'Nothing Found', 'twentyeleven' ); ?></h1>
It should say the name of the text domain being used!