Oh yeah, I also got the source from their home page and found that the main form targets an ASP page. So unless they're running ChiliSoft (unlikely), they're running Microsoft.
So Netcraft shows plannedparenthood.com is actually or has been running on linux, and your other supposed example communism.org actually has this right on the front page:
"An example of communist work relationships is provided by the Linux computer operating system"
http://www.communism.org/
So much for your diversionary defense of Howard Dean and his open source commitments.