I think "involving regulars" is key -- Mycroft Holmes' gentleman's club comes to mind for some reason, possibly the subconscious "Baker Street Irregulars" tie-in ... anyway.

hubski is 100% a third space, I have decided after reading some of that academic publication, and some Wikipedia. This got me thinking. Are twitter, certain subreddits, Facebook, et al. third spaces? Flickr? What are the distinctions of online third spaces? My instinct is that none of the above really qualify, and the main limiting factor/criterion I came up with was size. There are no true regulars on reddit, for example -- too big, too nebulous. I will say that I'm a member of two or three tiny subreddits that might qualify, and a forum or two elsewhere.

Rules of online third spaces include all of those quoted above, definitely, plus the aforementioned size limit, and also something less tangible that I'm not sure what to call. "Amount of sharing" or "non-anonymity," maybe.

Because forums only become third spaces when I've gone on long drives or caught a plane to visit someone I met there, when I've exchanged Skype information with people I've previously only communicated with via text ... subreddits become third spaces when I've uploaded pictures of myself doing the activity the subreddit is based upon, or pm'd personal conversations and made connections ... hubski becomes a third space when I have real conversations like this one, or when I listen to thenewgreen's album, or when I read #poetry. And so on.