Just chiming in here, my traffic on my sites receives more mobile traffic than desktop browsers these days; I would highly advise to everyone to take the time to build a mobile friendly design for your sites; you don't have to shove a million ads in your sidebars, you can modify your forums to place additional ad spaces within the product (like what I do
here).
Running a mobile friendly site, especially if you deliver your content over a secure (HTTPS/SSL) connection will increase your traffic.
