I'd guess that the guys like Guido, Linus, etc get jobs that a) pay pretty well, and b) Let them do pretty much what they would be doing anyway..
http://www.businessweek.com/magazine/content/05_05/b3918001_...
"For his part, Torvalds has been amply rewarded for his role, but he's no Bill Gates billionaire. OSDL pays him a salary of nearly $200,000. In addition, he sold initial public offering shares that he got as gifts from a couple of Linux companies, including VA Linux Systems. That helped him afford his house and put money away for his daughters' educations."