I've got a few patches available in my notmuch repo:

  http://git.pioto.org/gitweb/notmuch.git

The 'noarg-count' branch makes `notmuch count` without any argument
simply return the total number of messages in the database. This seems
like it could be useful.

The 'new-unread' branch makes `notmuch new` only tag messages as
'unread' if they don't have a maildir 'seen' flag. This shouldn't affect
anyones existing database, but should make initial imports for people
migrating from other mail setups (like me) go much better.

-- 
Mike Kelly