Not familiar with what a "Black Hat" is? Well, in the search engine optimization industry, a black hat would be considered a person who uses SEO techniques that are not in accordance with the search engine's terms of service. Matt Cutts, being the head of Google's Search Quality team, would make for a funny "black hat."
But Matt himself says so on Sphinn:
For my job duties, it's important to be able to step into the black hat mindset. That game was interesting because I got to test my black hat abilities without it causing any harm. :)
Wish I was there!
Forum discussion continues at Sphinn.