Cowboy coding seems interesting, and it might be just that I have been doing when developing Madcow, a PHP web framework.
However, it is not the same as Scrum. Many projects tend to fail using the Scrum methodology, possibly because of the lack of clearly defined roles, and then fall back to something looking like Cowboy Coding.
Unfortunately, it seems that the project I am currently working on at work is exactly that, Cowboy Coding, not Scrum…