I've been following the activities of educators and ed-tech folks in Second Life. It seems like it could be a really compelling virtual environment to help enhance online learning, by providing a shared quasi-physical face to face venue for distributed groups that wouldn't otherwise have one.
The amount of effort and care being put into these virtual places is stunning. The architecture is impressive, and the potential to create your own regions is compelling.
There are some amazing, interesting, and cool things being done in SL. For instance, the Space Museum, where you can walk around, climb on, fly over/through what appears to be every space craft ever created. Sit on top of the Space Shuttle, and see just how much taller the Apollo rocket is. And how much smaller SpaceShipOne is. Walk up to the Hubble Telescope and see an animated cutaway showing the lightpath through the instrument. View a simulated solar system, complete with orbiting planets.
Second Life - Flying around rockets: Taken while flying around the Space Museum in Second Life.
Second Life - Solar System Simulation: Taken in the Space Museum in Second Life.
What I don't understand is the faithful reproduction of the physical environment, warts and all, in the creation of other educational spaces. I don't want to pick on any organization or group, but I have seen two separate education-oriented SL places, and each has involved exact reproductions of lecture halls. Dozens of seats, aligned in rows. A stage with a podium. A large screen.
Second Life - NMC Classroom
It's an obvious first step, but in a simulated virtual environment, why would you willingly apply the same constraints as a real lecture hall? Why would you create a place where there is a concept of a "bad seat". Where your "view" of a presentation can be obstructed. Where the number of available seats is limited. It the case of the screenshot above, the audience is limited to 32 members, unless people are willing to "stand".
I'm not sure how Second Life would be applied in a real education setting, as compared with something like Croquet , which is more of a collaborative workspace environment (think Hypercard, rather than The Sims™).