absolutely! even if it doesn't directly affect CD sales and the like, it's a great way to keep everyone aware of performances and other musical (and personal) events. It simplifies the task to find interested listeners through it. When someone asks "what kind of music do you play?", you can simply direct them to it and voila, they can check you out and decide if they might want to hear more.
I'm at www.myspace.com/seancsinback