We talked with some of the brains behind Virtua Rasa, a new Virtual Tabletop designed from the ground up to be as close to a real tabletop experience as possible without feeling like a video game.  They have an augmented reality system you have to see to believe.  Right now, system agnostic and there's a great wiki function.  We talk about where they see the system going and the unique features Virtua Rasa offers.  Highly recommend checking them out.