How have you implemented the Presenter pattern?

Quick ping to see who's using the Presenter pattern (as described
wonderfully here:
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

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

Thoughts? Pointers?