I love SEO topics where there is no solid firm answer and one of those areas is mobile SEO. Google has no clear guidelines on how you should set up your site properly to handle mobile users and mobile bots. They tell you to treat Googlebot mobile like you would mobile users but not exactly how to structure your site for it.
Do you use mobile URLs, do you use the same URL with a mobile template. Google says, you can do both. But which is better. This is where there is a split in the SEO industry on expert opinion. I think it depends but most of the time, for SEO purposes, use the same URL, with a special mobile template.
Google's John Mueller said yesterday in a Google Webmaster Help that the easy solution is to go the one URL route with a special template. He is specifically replying to an issue with redirects for a mobile SEO strategy gone wrong. He wrote:
An easier solution, if you can do it, is to just serve smartphone and desktop users from the same URLs, using something like special stylesheets or CSS3 media-queries to optimize the content shown on smartphones. The advantage of that is that you don't need special URLs, think about the crawling and indexing of them, nor would you need to consider how you'd redirect smartphone users.
John then links to an article from a year ago, which I personally think confuses things a bit more.
I really want a definitive answer from Google on mobile SEO best practices, but honestly, it is changing so rapidly, it might be too much to ask for.
Forum discussion at Google Webmaster Help.