http://wiki.magrathean.ca/index.php?title=DGiG

Magrathean Technologies has configured up a special version of Mandriva Toronto Linux and OpenSim software to create a (pretty much) load-n-go local grid simulator. Put it on a server on your workbench, power it up, and with a bit of fiddling, you'll be able to log into an empty grid. From there, you can build, upload textures, terraform and may other functions.

They are working on ways to save the data from your local grid and upload it into the Second Life grid, but presently, there isn't a way to do that. In fact, right now, it's difficult to even save at all what you have done in your test bench world... once you reboot the server, all your work is gone. There are some work-arounds to save the virtual memory the sim uses, but right now things aren't pretty in that area.

However, it is very exciting that things like this are already available. It really speaks to how much cool stuff we'll have in the near future. :)