How have you implemented the Presenter pattern?

Quick ping to see who's using the Presenter pattern (as described
wonderfully here: http://blog.jayfields.com/2007/03/rails-presenter-pattern.html)
and how you've implemented it. We're looking for a good best
practice(s). Here's where we've run into a small issue.

Presenters aren't models, so they don't belong in app/models.
Instead, we're building a hierarchy of Presenter classes in our lib
directory.

This is working quite well. But we ran into an issue with the built-
in Rails helpers. We want access to them from our Presenters, but
since they aren't subclasses of ActionView (should they be?), we can't
call them -- we run into uninitialized dependencies deep in
ActionPack.

Thoughts? Pointers?

--dwf