Are questions about conventions and other RPG events on topic?
Most of these type of questions are
On Topic, but many are also
Too Localized. That is they only apply to a small period of time or a single location. That doesn't benefit the site as a whole. Certainly anything asking about "Dragon Con 2010" would be far too localized.
Very good questions, and I personally would say, yes. They are, but not for organization (such as "who is coming ?" or "where can I find the tickets?").
Yes, these questions are perfectly on topic. Ask away!
"Too localized" is no longer a close reason, but localized questions still pull from a limited pool of experts. While that doesn't make questions about such events off topic, it does mean it may take a while for you to get an answer, and some questions may never be answered. This is ok.
Also, we have a number of community organizers and other people heavily involved with most major RPG conventions, as well as people who were involved with some major RPG conventions back in the day, so this is actually a pretty good place to ask that sort of thing.