From the 'don't mess with Apache' files:

The Apache HTTP open source web server (I usually just call it Apache, but Apache is more than just web servers these days..) gained over a million new sites for the month of January 09, according to the latest stats from Netcraft.

The Netcraft study does not measure the number of actual Apache installations (that is physical machines) but rather measures the number of sites (essentially domain names across all TLDs) that are being hosted on a particular servers.  For January of 2009, Netcraft reported that Apache gained 1.27 million sites while Microsoft's IIS lost just over 2 million sites.

All told Apache now accounts for nearly 97 million sites or just over 52 percent of all sites measured by Netcraft. Microsoft's IIS still holds down second with just over 61 million sites or 33 percent of the Netcraft survey.

While it's interesting to note that Apache still is the majority - Microsoft's share is certainly still large and impressive. Added to that is the fact that in recent years a new challenger has emerged in the form of Google with its GFE (Google Front End) web server. In the January 2009 Netcraft survey GFE represented over ten million sites.

Lighthttpd which is a neat project that I track is just starting to show up to with nearly 3 millions sites.