Is is possible to connect the SE chat to iChat? I am not always on SE, but I am on iChat a fair amount.
SO Chat is custom-built, so it doesn't work with any other services.
However, given that the SO crowd consists of programmers, several projects have been proposed/begun to allow more functionality:
Unfortunately, none seem to have had much action lately, so I don't know the current status of any of them—but something along these lines will be your best bet.