A blog is short for a weblog.
http://pinds.com, http://scripting.com, and http://boingboing.net are examples of blogs.
A blog doesn't have to be maintained by any single individual. It can be maintained by a group of people.
In this instance, whenever someone makes changes of a general nature to the OACS tree, we'd post it to the blog, so other people could see what was going on.
We'd want to integrate with notifications, of course, but I'm thinking of doing that anyway, as soon as I get my own site upgraded to 4.5.