Assume that I have a WordPress post with a URL of http://example.com/2011/10/hello-world. Without hum installed, I can enter the URL http://example.com/hello and WordPress will redirect to the full URL for the above post. With hum installed, it redirects to http://example.com/hello/ (just adds a trailing slash), and loads the front page of the site.
When the requested URL does not explicitly match a hum URL, it should fall back to the standard WordPress logic.