Yes, you can set a rewrite in the default site itself. Any hosts that do not match any of my listening servers, are redirected to a default site.
Hope that helps. Of course you can make more rules of course.
Options FollowSymLinks MultiViews
allow from all
# This directive allows us to have apache2's default start page
# in /apache2-default/, but still have / go to the right place
RedirectMatch ^/$ http://www.myserver.com/