Never knew about this feature. Apparently greater gods have been using this for a while. There is this neat feature in WP that allows you to make your URIs even nicer. Consider what is better

http://www.pnarula.com/2004/05/15/this-is-my-first-post

or this

http://www.pnarula.com/2004/05/15/firstpost/

In the first example WP is creating the post-slug automatically by using the title, I never bothered to edit it. Now after reading at LibaryPlanet I have seen the light and URIs are much nicer. Do yourself a favor and start editing those post-slugs.

End Note: This is only available in WP 1.2.