A few days ago Google announced a change to their algorithm that really favors sites that are built using the best in class design patters of Responsive Web Design (RWD).
According to Search Engine Watch Google has really made the way you put together your mobile site even more important.
The main emphasis of their post is this: if in doubt, connect the user to the content they want on a non-mobile page, rather than direct them to an incorrect mobile-formatted page.
For instance, having a blanket redirect to your mobile homepage when the site detects a user is on a smartphone, despite the fact they have clicked on a deep link, has now been called out as an explicit no-no
I think we all probably believe that RWD in some form or another is the future of the mobile web, but this move by Google might just be the update that the rest of the world needed to push the strategy into the main stream. Clients are used to SEO conversations and so explaining this to them and getting them to realize they need a new Responsive site, should be a no-brainer.