Monday night I attended an NMC Teacher's Buzz session on educational gadgets for SL. You can read more here:
http://sl.nmc.org/2008/02/06/gadgets-galore-thats-the-buzz/
I'm starting to see a good trend here - off the shelf tools for free or reasonably priced. It's not just enough to know how to navigate SL - you also have to have a good grasp of the educational possibilities. Then you have to build or find the in-world tools that enable your vision. For now, you have to dig fairly deep into the educational community to find these tools. A quick question to a list usually will point you in the right direction. Next year, I'd like to see big repositories of tools for education, along with best case uses of these tools.
NMC is working on this, as is InfoIsland, and also the Salamander Project. When we have enough of these in place, we'll see the next surge in SL for Education use.