I can't recommend [link|http://textpattern.com/|Textpattern] enough. I keep hearing good things about Drupal and Mambo, but I think they're a bit too complex to set up and manage. (My view on a CMS is that I should be able to configure it and then hand it over to the client; if they need to come back to someone like me to manage and update their site, then the CMS isn't doing its job.)