WordPress

FreeBlogIt
Offers free and paid service multi-user WordPress blogs. Design templates and support forums available.
http://freeblogit.com/

Linux Admin
Fully managed WordPress blog hosting clusters with high availability and failover.
http://www.linuxadmin.org/blog-managed-hosting.php

WordPress.com
Free blogs managed by the developers of the WordPress software. Includes custom design templates, integrated stats, automatic spam protection and many more features.
http://wordpress.com