I've recently been introduced to Terra Nova. These are most definitely the smartest people around working with Games and Learning. If you are at all interested in the learning potential of online gaming then you will most definitely get lost for hours as I have done in the past.
This post titled Are Virtual worlds Good for the Soul? is an awesome anecdotal account of a Behavior Intervention Specialist utilizing the MMO World of Warcraft as a therapeutic tool for his challenged kids.