So yeah, ARR or Application Request Routing is a new feature of Microsoft’s IIS 7 and 7.5. Basically among other things it allows reverse proxy.
What does this mean? well up until now i have run wordpress and joomla under IIS with Windows running PHP. This works, pretty well actually but you still find that plugins and some features of applications like wordpress still require linux.
Run it on linux or sometimes referred to as LAMP (Linux Apache MySQL PHP). Use ARR via URLrewrite to send all requests for wordpress and joomla based sites to the linux server. This enables me to still run my Exchange web access to my HD2 and a LAMP environment, giving me the best of both worlds.
The process is quite straight forward, simple install and enable ARR then create a site for the web page you want to serve. On the site click URLRewrite and select reverse proxy rule under new rule.
Ensure you put in the host header of the site you are configuring and the ip address of the linux server. Be sure to check the outgoing rules and viola! a WIISLAMP (Windows IIS Linux Apache MySQL PHP) environment.