According to netcraft's latest survey IIS' marketshare has increased by 0.36 reaching 31.49 while Apache's marketshare has dropped from 58.86 to 56.00!
Go IIS!
And after IIS 7.0 (with Longhorn Server) I expect IIS to be the monopoly leader in Web Server industry. Believe me, IIS7 is revolution.. 
BTW, boo-hoo, it looks like the "Open Source Parking Headers Spoofing" initiative hasn't worked at all 
Stay tuned.. 