NGINX takes 2nd place in Web Servers from Microsoft IIS
zdnet.com
zdnet.com
EDIT: My title was also better.
[1]http://news.netcraft.com/archives/2012/01/03/january-2012-we...
Apache still blows them out of the water though.
(Ignore the pre-August data, it's before we had a real sample size.)
Personally I use Nginx > PHP-FPM, so there is no other web server on the box.
Benchmarks on my projects show that the difference is insignificant. Since I currently do not have memory constraints I am still using nginx + apache with mod_php.
But like I said, nginx is great for doing loads of things and I sort of "quit php" recently so I don't really care about php performance anyway.
IIS is still 2nd place if you look at the top one million busiest sites.
We've known for long time that horizontal scaling for large sites is only cost effective when you use an open source web server and aren't taking a hit for licensing.
http://www.codinghorror.com/blog/2009/06/scaling-up-vs-scali...
What other growth metric is there for a web-server besides market-share?
EDIT: BTW, I'm not an Apache fanboy. I recently moved my personal site https://grepular.com/ from Apache to Nginx. I just like using the right tools for the right job. And Apache is a great server and can be configured to perform extremely well. I've personally configured and run large server farms of Apache boxes in shared hosting environments.