During February 2011 we performed a survey of technologies in use by the Alexa Top 1 Million web sites. The aim of this survey was to get an accurate picture of the web applications and web servers used by the most popular sites in the world. In addition we hope to highlight the security importance of understanding the technology used, performing ongoing patch management and having a vulnerability assessment program.
See below for a summary of the Web Server Popularity, a summary of the CMS Popularity has also been published.
Click here for the full report (PDF)
Results from the survey indicate that over 27000 Blogger sites were found in the Alexa Top 1 Million. These sites do not advertise a HTTPServer header, so it is likely that the count for Google Web Servers is higher than in the chart. It is also likely that the total number of sites of all the above servers is higher than that indicated as a large number of sites are obscuring the advertised version in the banner (this is good practice from a security perspective).
The breakdown of Apache major versions is interesting; especially when the fact that Apache 1.3 is no longer maintained is taken into consideration.
Not shown in the above chart are the IIS versions 3.0 and 4.0 that were found 6 and 69 respectively from the Alexa Top Sites. That is some seriously old web iron running those (NT4.0 and Win2k). 
