Application Request Routing (ARR) v1 released today! The ARR feature is a free IIS7 extension that extends the Web server UI and runtime to:

· Achieve high availability and scalability.

· Enable elastic scalability for shared hosters.

· Dynamically load balance web requests (to be used in conjunction with existing load balancers)

ARR enables the following scenarios

· Easily add server capacity as the demand for their web application increases 

· Seamlessly deploy or upgrade web applications without downtime

· Shared hosters can offer elastic scalability and change the business model based on resource consumption

More details at http://www.iis.net/extensions/ApplicationRequestRouting