Anyone who is a registered user has the ability to do their own blog here. Be careful, because anyone else can make comments to it! You'll know who your friends are.

Creating an entry: In the left menu, click on Create Content. Then on blog entry.

Anyone can view it, but you must be a registered user in order to post to it. It works about like any other forum on the web. I may add some notes if I find some quirks.