Many teachers have class blogs, where they post homework assignments, make announcements, and so on. In many ways the class blog can replace a class Moodle, hosting links to video clips, hyperlinks to resources for assignments, etc.
It strikes me though that Moodle works far better for that sort of thing because it allows students to submit their work, and get feedback! But the blog does have a crucial advantage, and that is the neat way in which comment is enabled.
Moodle has a class blog utility, but it is so clunky it almost puts you off writing altogether. A well designed class blog, however, could easily be used to facilitate class discussion. And when supplemented by a link to the class Moodle submit assignment button, you really have the best of both worlds. Moodle is also not very handy about allowing you to post presentations by students, whereas this could be done on the class blog quite easily, inviting comment on the presentation by other students.
Since blogs can be made private, with password settings, the class blog could be made quite safe and secure.