How to add tagging with autocomplete to an existing model in Rails?

Question

I'm trying to add "tags" to an Article model in a Rails 3 application.

I'm wondering if there is a gem or plugin that has adds both the "tagging" functionality in the model and also the auto-complete helpers for the views.

I've found acts_as_taggable but I'm not sure if that's what I should be using. Is there something newer? I'm getting results from 2007 when I google acts_as_taggable