Ben Brooks on having “mobile” themes for websites:
The issue isn’t that it is hard to build for mobile, but that it is unnecessary at this point to port your website for mobile devices. If you really find it necessary use responsive design from the outset, or at the very least give me an option to go to the full site.
It took me a while to come around but I am in the camp that mobile “optimized” versions are unnecessary. But in some cases they can be useful. But Brooks says, the most important thing to do is to have an easy way to get to the “regular” version of the site too.