Very nice annotated list of articles relating to educational uses of second life, second life and pedagogy, as well as second life resources of a more educational nature.
Another very useful resource of a more broad nature is the official second life blog;
the blog covers just about everything including lots of howtos and tutorials.
Also, John Lester out of Linden Labs (second life’s company) maintains a resource list at del.icio.us — lots of good and interesting stuff there. If you use del.icio.us, you can add it to your network or well, just bookmark it.