As a founding guest, I heard of i3 from a friend in NYC. Well hackerspaces.org he mentioned a few of his local ones, and we were thinking of starting our own. Then I found i3 meeting at a coffee house right down the street from me. Being unemployed for 90% of the first spaces life I became known as a founding guest. Which I gained my current job from being around members within the space and finally became a member shortly before the move to the new(current) space.
I started investigating hacker-spaces after seeing AHA at the DIY sale in the state or fox theater downtown last year. I3 was the closest, I read the wiki and realized that long ago I was invited to a early planning meeting but flaked out and forgot about the whole thing. I'm glad someone went to the boring planning meetings to help make I3 what it is today!
Likewise, at Penguicon - I attended the hackerspace talk i3 put on, and I've been lurking the public mailing list since. But I plan to make the trip to the space soon!
I first heard of i3 when I saw the cupcake mobile at Future Midwest. Then I went to i3 for the first time for a #tweetea in February 2011 that was co-hosted with Girls in Tech.