It's common in many bulletin boards -- folks post a question, but don't follow up when replies are received. I'd like to see 'em participate more, but I can't force people to post.
As for registration, it's a must -- to prevent spam, maintain consistency with user identification (on the old boards, some folks used several aliases, and they weren't even trying to sockpuppet), and permit the more advanced features of vBulletin to be used such as private messages, post counts, and so on. Registration is tandard operating procedure on most Web-based bulletin boards now; there's few places online where you can just post and run. (There's one shortcoming to registration; when you're known on the board, and want to post a message for help regarding a planning issue that you're embarassed to find yourself in, where you feel that you could possibly lost the respect of your peers.)
As far as increasing participation, I think there needs to be more casual chatter around here -- in the appropriate boards, of course. I sometimes visit one "armchair urbanist" related bulletin board that had several times the participation of the Cyburbia forums. These weren't professional planners talking about setbacks and signs, but "city geeks" casually discussing the built environment and comparing cities; i.e. "What's better, Seattle or Denver?" While Cyburbia is geared towards professional planners, "city geekery" and more participation by those who aren't professional planners would be welcome.
There's plenty of folks from outside North America that are registered on the Cyburbia bulletin board, but they hardly ever participate. Planning discussion seems to be NA-centric, but there's hardly any participation from those in English-speaking countries outside of NA that have US/Canada style planning systems, such as Australia, New Zealand or South Africa. Hardly a day goes by that I don't see a registration from folks in Sydney or Jo'burg, but they're obviously keeping quiet.
