Recently I wrote an article exploring your options for automatically publishing your website updates to social networks, which you can find here:
Another option that I just discovered is dlvr.it (read "deliver it"), which is a service for automatically publishing you website updates to various social network websites like Twitter, Facebook, and LinkedIn. You can sign up for free here, all you need to provide is an RSS/Atom feed for your website to get you started:
Updated 2022 : note that the above post was originally published in 2010, but is left here for archival purposes. The dlvr.it service is still running, but I have not used it since writing this post so cannot comment on the latest version. I have also fixed a few links that were broken.