In 2003, SixApart released Movable Type version 2.6, which included options for Creative Commons licenses. At the time, I was (and still am) very impressed that Creative Commons licenses were built right into the code of a popular weblog software application. Yochai Benkler's framework of layers is applicable here; Movable Type has Creative Commons embedded into the logical (code) layer. Creative Commons' own use of metadata for RSS and searchable CC-licensed content is an instance of this as well.
I believe, if I'm not mistaken, that WordPress has a plugin that lets you choose a CC license within WordPress also, but will a WordPress user please confirm this? I have a wordpress.com account, and I poked around in the dashboard but couldn't find CC license selection anywhere in the options. Drupal has a Creative Commons module.
Finally, are there other weblog software apps which have CC license selection built into the core software code, or which have CC license selection plugins? Doesn't LiveJournal have a CC option now that they're affiliated with SixApart? This information will help me with a paper I'm revising.