I think Linus refused to work for any Linux company since it would create a conflict of interest for him and give the company an advantage. Now through the Linux Foundation he can work for all the Linux companies at the same time.
I think he also received a buttload of stock from Redhat? as a thank you for pushing the OS forward. I'm researching where I heard this from now (anyone have a link?)
"Red Hat and VA Linux, both leading developers of Linux-based software, presented Torvalds with stock options in gratitude for his creation.[13] In 1999, both companies went public and Torvalds' net worth shot up to roughly $20 million.[14][15]"