You're better off getting a response here. I think I've put up three or four topics, none really got replied to (constructively anyway). They're littered with spammers, and the admin doesn't seem to care about what happens to them. I've PMed them about it but they just ignore it. They asked for mods, but I haven't seen anything come of it. There's really nothing there to draw the ZF user in. I get faster answers in the middle of the night here on #zftalk than I do at zfforum. Not to mention that they have theme issues and refuse to fix them (they're easy to fix).
Oh, and Jelsoft doesn't run it. Jelsoft is just the company that owns vBulletin. So they're using the vBulletin software, but they're not run by Jelsoft. As far as I know, it's just some devs from Zend that are running it, but I can't be sure.