There are some newcomers around in the web server arena as well as improved ones (including cloud stuffs).
I've been using G-WAN for almost 3 years and I recently benchmarked it Vs. Apache2, Cherokee, Lighttpd, Monkey and Nginx (this last one being the fastest of the previous 4).
I know that some "geeks" will argue: "Hey, it's a free shareware but not open source!" like if they never use proprietary tools (video drivers, flash readers, mp3 codec, etc.) and as well as if they are able to modify the Apache2 or Nginx code!
So, I don't care since it's 2 to 3 times faster, delivers over 3 times more requests per second and needs less CPU and RAM resources than the best Nginx (see the benchmark here
Even more, there is absolutely no headache with configuration files. Just unzip the G-WAN folder and it runs instantly.
Want to make a more complete test, I wrote an install script to help setting up all the available languages as well as all the dependencies used by the sample servlets here