I don't feel the same about SO not being a community.
Even though I'm not a very active member, I'm in contact with quite a few people I got to know from SO and even met some in person.
In my opinion it's just that communication doesn't happen mainly on SO itself. As far as I understood the discussion (more methods for interaction have been suggested since the beginning of SO) this is deliberate.
The problem is mainly that chat.SO sucks in a lot of ways and probably should be reduced to a single room where all SO regulars who have time to chat do chat - together. That's the way pretty much all other sites do chat (including MSO) and it's... saner. I just don't know how much it'd scale.
That doesn't work for interest-specific communities. HTML5-ers, Java-ers, and haskell-ers will probably not talk about the same topics with each other as they would with other people that share their interests, as in their own interest-specific community.
Isn't that why on freenode, you have communities based around particular langauges? #java, #haskell, #html5, etc. etc? Not to mention social versions, like #haskell-blah and what have you.
It really does feel great to have an answer accepted, you get something similar to that feeling of "ahh this is fixed, finally!".
I am a tex.stackexchange.com regular and I really like the community. It is a small community but/therefore quite some people meet on a regular basis, the (local) TUG conferences. I agree very much with the "thank you sx" note.
And while my interaction with askers is always fleeting, I'd really like to thank them for all their support. At the end of the day their words are the only encouragement I need:
http://i.imgur.com/POZmt.png