I don't think it is just cooperate worship. I think there is way more to fellowship. If at the church I would think that it would be interaction between congregants about primarilay religious topics with the how are things going type interaction and maybe the sharing of a joke or something none serious. A mix of things if you will.
Nice thread. I do think it is one of the things a person should look at when considering a church. Of course theology matters at least on the basics.