When it comes to the scalability of web servers, first thing customers think about is scale out. While scale out is great option, there are many scenarios which can benefit from scale up. In Windows Server 2012, IIS team has done a good amount of work to scale up IIS server on latest industry standard hardware.
IIS team, along with HP and Microsoft EEC has recently published a case study on how IIS 8.0 performs on HP Proliant DL980, an 8 socket, 80 core machine. Please check out http://www.iis.net/learn/get-started/case-studies/case-study-iis-80-scaling-on-an-hp-proliant-dl980-g7-8-processor-socket-system