The Taggit filtering API has changed as of version 0.9.0. From the Taggit changelog (http://packages.python.org/django-taggit/changelog.html):
Backwards incompatible Filtering on tags is no longer filter(tags__in=["foo"]), it is written filter(tags__name__in=["foo"]).
update SnippetManager matches_tag method to use current (as of 0.9.0)…
… Taggit filtering API
yo i just fixed the one place it was filtering on the slug instead of the tag object itself. everything should work with 0.9.1