I'm a wurfly wurfl, yeah. We're all wurfly wurfls, yeah.
I almost can't use this because it's named WURFL. Also I have strongly mixed feelings about device detection.
By default I am opposed to making assumptions about what content someone might or might not want to see based on what device they are on. Plain old responsive design with good markup and content structure and smart CSS should be able to handle just about anything. But, used thoughfully and sparingly, this WURFL thing could be a useful for more complex situations.
One such case we're dealing with on a project now is some requirements for analytics, where it's necessary to detect device type, so there you go.