We now have a wiki but currently it's almost completely unchanged from the default install. It's up to all the jEdit users to turn it into whatever you want it to be. Get a user name and go to work. Almost everypage can be edited by anyone. If you've never used a wiki before you can play around in the Sandbox web to try things out. Some content suggestions to get you started:

Configurations for working with java, C++, HTML, etc

Tips for people switching from Emacs, vi, bbedit, ...

Feature suggestions for jEdit or plugins