Team blogs are quite useful when small groups of people wish to contribute to a single blog. Basically, one person initially creates the blog, then adds other people to it as members.
Team members can either be administrators or not. Administrators can edit all posts (not just their own), add and remove team members (and grant admin access), and modify the blog's settings and template. Non-admins can only create and edit their own posts.
Here's how to add members to your blog:
First, go to Settings | Permissions:
Then click Add Authors:
To remove a team member, go to the Settings | Permissions tab and click the "remove" link of person you want to remove: