I work remotely for a very distributed organization (Mozilla), and still get a lot of informal interaction. The key is to have several different communication venues with different standards and expectations. Discussion in Bugzilla is fairly technical and work-oriented. Discussion on mailing lists allows for more advocacy. IRC allows for more chatty, non-work-related talk, and some IRC channels have different rules than others. We also use Twitter, private email, internal web forums, internal and external wikis, Rypple, etc...