A good thing Dave Chaffey tweeted a link to Gary Robinson's article . I got hooked on this immediately, and I was analyzing mobile visitors to my site literally a few seconds after reading Gary's post.
About 3.5% visitors see my website via mobile devices
Regardless of the small size of the percentage above, it represents (or translates) thousands of visitors each year
The three main operating systems in the last four months were: iPhone (58%), Android (13.6%) and iPad (12.9%)
The lowest bounce rate recorded with "mobile devices" has been with iPad users (natural, is not it?)
Start monitoring this particular set of statistics more frequently / closely
Work to optimize the experience of my mobile visitors (especially those who access the site on their iPhones and iPads)