First off all what is Erlang? Here’s description from the http://www.erlang.org/
Erlang is a programming language used to build massively scalable soft real-time systems with requirements on high availability. Some of its uses are in telecoms, banking, e-commerce, computer telephony and instant messaging. Erlang's runtime system has built-in support for concurrency, distribution and fault tolerance
First time I heard about Erlang was way back into 2007. At that time I thought about it as a great choice for development of the server applications such as game servers, instant messaging, etc.
Recently I was wondering if are there any Erlang frameworks for web development exists. And as you probably expected there are Many frameworks. I made some research of the Chicago Boss. And you know it’s just awesome! One of the greatest features is Zero downtime code upgrades in production.
I’m sure Chicago Boss doesn’t so mature as for example ASP.NET. But you know ASP.NET is a general solution. You can build any kind of web application using it. It could be regular HTML pages or highly interactive single-page application or just web service. I suppose Erlang (and Chicago Boss) are more specialized. For example if I plan to build web site with regular HTML pages I probably will rely on ASP.NET (or PHP). But for single-page applications with requirements on high availability I will consider Erlang (Chicago Boss) + HTML5 (jQuery, Knockout)