I'm personally of the opinion that Wikimania should remain very much a community event, and in fact bring it back to something closer to a retreat than anything else.
Venue is obviously a big factor, here: more people will drop in off the street for a well-publicized conference at Harvard than at a youth hostel somewhere in Europe. We were mindful of this when we chose the location for Wikimania 2006, of course, and felt that the various other benefits outweighed that drawback, but I was still disappointed to see less community interaction this year than at Wikimania 2005.
A bigger factor, however, and a somewhat controversial one, is the ability to buy conference passes for a single day only—especially the day of the conference, on-site. This year we did very well with preregistration, and actually booked over our numbers for catering and room capacity. We closed registration altogether a few days before the conference, and although I made a number of exceptions, only one of them was for a Wikimedian.
In the last two weeks before the conference, the ratio of those paying the "outsider" rate to those paying the community rate was running just under 3:1. Although I don't yet have the final numbers, total attendance was split roughly 50/50 community/outsider. (This is a point in itself.)
For community members, the ratio of full conference passes to day passes was roughly 6:1. Outside the community, that ratio is 1.4:1.
These numbers should come as no surprise to anyone. It's common sense that Wikimedians don't wait until the last minute to decide whether or not they're coming, and that they're interested in the whole conference, not just seeing Larry Lessig. I wanted to be perfectly clear that the facts actually reflect that, however.
Day passes are fine for trade expos, but this is Wikimedia—our goal should be the opposite end of the conference spectrum. This isn't to say that a Wikimedian whose circumstances suddenly change three days before the conference can't buy a pass, or that someone who can only get out of school for a day has to pay the full rate, but I don't see the single-day pass coming back next year; neither can registration continue in full force up until the day the conference opens.
I think we need to market Wikimania very differently in the future, but the way we do that depends entirely on what form it takes, whether it's split up into alternate/sub-conferences, and how. This is where Delphine's "real question" comes in, and I'm glad it's being discussed. I have my own thoughts on the matter, but I'd like to see what people's initial thoughts are first.
Austin