It seems to me the UML module of NetBeans is a bit too much hidden. In NetBeans 6.5 it was very easy to create an UML diagram. No plugin installation necessary or sth. like. Read my post where I found a zip file to install the UML module.
And now, after this procedure, I got the UML module back, but it seems to me that I cannot create class diagram with it. Do you know how I can do this with NetBeans 6.8?
Update1: There seems to be no support
Update2: Nevertheless somebody seems to got it working.