For some (totally unnecessary) contrast with Netcraft's August 2005 web server survey, here's an excerpt from a MS-favouring survey at port80software:

Before looking at server market share in more detail, it is important to note that the vast majority of the Top 1000 Corporations' Web sites identify their server software platform in their standard HTTP header response, and thus fail a basic security test. Come on Fortune 1000, make our jobs more difficult!