- They understand presenters. Want to speak at JavaOne? Last time I tried, you have to have your slides completely ready months in advance. No last minute changes allowed. Given the velocity at which development is changing, that means that by the time of the show, everything you might want to talk about is irrelevant. At qCon, nobody asks for your slides in advance. Rather, they know that we're all doing last-minute revisions until 2 minutes before you go live. So they just walk up with a USB key while you're still onstage and grab them right there and then.
- It's not single focused. While I think that there are places for single-focus conferences (whether on programming languages, methodologies, or specific technologies), it's hard. Getting people together requires at least a couple of days of content, and how much content can you put together on one single subject without it getting boring and repetitious (and thus Preaching to the Converted, as the only person who wants to hear 3 days worth of "Scrum/Perforce/Ruby Is Great" is someone who wants their worldview validated by others).
- It has the right number of tracks.By having about 5 things going on, you always have a choice of something interesting to see, but you're not so spoiled for choice that you get frustrated that you can't go to half the things you find interesting.
- They grab practitioners. This is extraordinary, because there are a lot of people that showed up to give presentations who aren't prolific bloggers or writers or speakers. You get to have their experience where they have maybe one or two things they can/want to talk about a year. That gives you remarkably deep access to senior technologists that you wouldn't otherwise get access to as part of the online development conversation (the guys who show up and present at every single conference you can't seem to get to shut up sometimes)
- Free Beer. Seriously, while I expect that tonight there will be many people down t' pub, hosting a free beer night got lots of side conversations going fully lubricated by alcohol. While not a ton of technical content probably got disseminated, people made contacts and generally talked about what they're doing and why.
: Guilty! When I worked at M7, I was the designated thinly-disguised marketing shill at SDEast and BorCon.
: Turing Award Winner in da hizzy! Also, best quote evar: "QuickSort was only the second algorithm I tried to write." Wow.