Matt Cutts is back at work, answering queries and clearing confusions. The latest question is "Does Google make any distinction in scoring between Apache, IIS, or other web servers?"
Matt answers “Nope. You can use either web server and Google will rank the pages independently of the web server platform.”
But someone in AdSense mentioned an interesting case that they’d heard of. Apparently, doing url rewrites in ASP .NET 2 can sometimes generate an HTTP status code of 302 instead of a 200. This issue isn’t specific to Googlebot (it would impact any search engine bot). The best write-up I’ve seen is at http://communityserver.org/forums/536640/ShowThread.aspx. Looks like one of the first places noticing this was here.
Matt suggests Fiddler for Windows, Live HTTP Headers extension for Firefox to see the actual request your browser sent, and the raw reply from a web server. He also reccommends Google’s Sitemaps tool as well. For more visit his blog.