If you have an hour–lunch, e.g.–watch this thorough presentation on Second Life, including the history of virtual worlds in education and a terrific overview of how SL works.
The presentation technology also allows you to select topics and/or slides in the presentation, so that you can view something that interests you.
The presenter is Ross Perkins / Milosun Czervik, SL of Virginia Tech. I think you’ll like his objective stance that doesn’t try to wash away valid criticisms of SL.