For all the newer people, I encourage everybody to come by the HN secret cabal IRC channel, #startups. I found that the term "secret cabal" really sounds much more exciting than the actual channel ;)I try to go by at least once a week, though. It's fun to be in more of a real-time discussion.

I would also encourage people to look up folks' email and email them with questions and such. Great way to make new friends. Many a time I've tracked somebody down from an HN discussion only to have it continue via email. (It also brings the noise factor down over here, which is always a good thing)

I know a lot of guys follow everybody they can from HN on Twitter. I don't know if I would personally go that far -- Twitter has a hecuva lot of noise and I get easily distracted -- but it works for some.

So yes, there's a lot of out-of-band chat going on, but as far as I know, none of it is exclusive. If you'd like to participate more, the same channels are open for anybody. I know I keep my Twitter, Facebook, and email addresses in my profile for just that very reason.