There is a list of papers about VSP in the wiki
http://www.openvsp.org/wiki/doku.php?id=papers
There are also some video tutorials put together for an older version
of VSP. I haven't linked to them from the main web site yet, but you
can get to them from
http://www.openvsp.org/vid_tutorial.html
I have some other documentation, but I haven't had the opportunity to
get it online yet. Hopefully soon.
Rob