Guess who?
You probably already knew about that but i just learnt about it when i as searching for GPL licensing of a distro one. Yahoo search provided me with the link.

Microsoft.
Link: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.htm&r=3&p=1&f=G&l=50&d=PALL&S1=6727830&OS=6727830&RS=6727830

Inventors: Lui; Charlton E. (Redmond, WA); Blum; Jeffrey R. (Seattle, WA)
Assignee: Microsoft Corporation (Redmond, WA)
Appl. No.: 195256
Filed: July 12, 2002