How have you implemented the Presenter pattern?

Quick ping to see who's using the Presenter pattern (as described wonderfully here: Jay Fields' Thoughts: Rails: Presenter Pattern) 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