Rails - Oct 2009 - acts_as_taggable_on_steroids

hi,
i''m playing with acts_as_taggable_on_steroids plugin and i find it
very nice but i got  stuck on find_tagged_with ordering options.
suppose i got a model "book" that acts_as_taggable.
when i search for
Book.find_tagged_with(["a","b","c"]) i got the
books
that have any of these tags.
Is there a way to order them, giving me the list in descending order?
i mean, books with all tags first, followed by books with two tags and
so on?