Apache2: How To Redirect Users To Mobile Or Normal Web Site Based On Device Using mod_rewrite

Since the massive rise of mobile devices, smartphones, and tablets like the iPhone, iPad, Android phones and tablets, BlackBerries, etc. you might have considered creating a mobile version of your website. This tutorial explains how to configure Apache to serve the mobile version of your website if the visitor uses a mobile device and the standard version if the visitor uses a normal desktop PC. This can be achieved with Apache's rewrite module.

Source: Howtoforge Linux Howtos und Tutorials