How to enable a theme for your Magento mobile web site?

You can use execeptions (the good kind) to show different templates on mobile devices.

To add exceptions for the mobile devices, navigate to the Magento administrative area -> System -> Configuration -> Design -> Themes. Click on the Add Exceptions buttons besides the Templates, Skin and Layout labels.

Enter the following line in the Matched Expression field:

iPhone|iPod|BlackBerry|Palm|Googlebot-Mobile|Mobile|mobile|mobi|Windows Mobile|Safari Mobile|Android|Opera Mini

In the Value field enter the name of your newly installed mobile theme and Save the changes.

Then you can open your web site through your computer and your mobile phone. You will see that it loads with two different themes depending on the device.