Matt McAlister has put together his first screencast showing some of the various tag-centric navigation systems he's found of interest. The examples he uses are good pointers to some of the emerging IA trends we'll see incorporated into more and more sites and services.
Matt works at Yahoo's social media team, so if nothing else you'll get a sense of how one of the company's product managers is thinking about this space.
As an aside, I love the screencast format, especially those that aren't necessarily trying to pitch a product or service. It's a very effective way to communicate ideas and thoughts - a recorded audio / visual stream of conciousness.