Some interesting examples of science being done in Second Life. It's fine to use a virtual world as a social environment, but how can we construct virtual 3D labs to use for collaborative science? The only examples I have seen live is IBM's virtualization of proteins, and a visualization of starts in 3D. mainly useful for instruction, rather than experimentation. I think there is still some possibilities for exploring other kinds of 3D visualization. If the manipulation of point-of-view could be made more natural. At the right, an avatar explores a virtual 3D portion of the stellar neighborhood. Below, IBM's protein display at Almaden labs.
Update (from the comments): Chemistry in Second Life.