From what I remember from the WebCT North-West User Group, WebCT 6.0 has an add on pack which contains blogging capabilities among other things.
There is a short debate on James Farmer's blog about the worth of these WebCT blogs, which is worth looking at (including the comments).
From these comments I'd think it better to set up blogging software on the server, as Warwick have. That seems to have worked well there, and a blogging culture developed. I'd guess that this is because students can write different blogs on the topics that interest them, rather than the subjects and contents being controlled by tutors?