Using a different theme on a subdomain with the same content?

I am looking to set up a mobile version of my site and would like to set up a subdomain with a mobile theme that still uses the same content in my “regular” site.

So if my site is at “myblog.com” I want to set up “mobile.myblog.com” which draws content from “myblog.com” but uses a mobile-enhanced theme.

How can I do this?