This is a simple Ruby on Rails weblog application with support for tagging, archiving and quick-search. It features a simple admin section with authentication and a focus on writing over all else. The app is therefore limited by default. You won't find a link list or del.icio.us integration or any of that. If you're looking for something more robust (read: bloated), check out Typo.
SimpleLog is written and maintained by Garrett Murray and released under the GPL license. In short, SimpleLog is free, must remain free, and cannot be used in a commercial application or included in anything commercial. See the LICENSE file for more.
A simple installation/usage screencast is coming soon. In the mean time, you can view some screenshots of the admin interface at Flickr.