I hadn't taken note of the market share numbers in a while but check out the results from the most recent Netcraft survey. They state the following:
"Microsoft continues to increase its web server market share, adding 2.6 million sites this month as Apache loses 991K hostnames. As a result, Windows improves its market share by 1.4% to 34.2%, while Apache slips by 1.7% to 48.4%. Microsoft's recent gains raise the prospect that Windows may soon challenge Apache's leadership position." ... "But if Microsoft continues to gain share at its current pace, it could close the gap on Apache sometime in 2008."
That is a substantial change especially considering that the percentages remained essentially stable through all of 2004 and 2005 with Apache leading by 30-40 points. Getting the gap down to 14 points is a significant achievment. Remember also that IIS used to be a toxic term in the late '90s and earlier this decade.
With the major improvements coming in IIS7 on Windows 2008, IIS may well become the leading web server platform in the very near future. That's a turn around that I don't think the team gets enough credit for.