Mark Shuttleworth delivering his keynote at Linuxtag 2006 in Wiesbaden.
Mark had founded an internet security company in the nineties and sold it for a ridiculous lot of money just when the internet bubble was about to burst.
He went on to become one of the very first space tourists.
Today, he's most popular for his Open Source engagement as the sponsor of Ubuntu Linux and probably the most prominent "pop star" character that the Linux community will see for quite a while.
In the photo, he's taking off his jacket and shirt to reveal a KDE t-shirt.
(2007/11/18: This is now available under a Creative Commons License. Please attribute as specified on my profile page.)