I was looking everywhere (as well as on Google's blog) and could not find a straight answer to this question: which URL is the best for mobile from an SEO perspective? Is there a difference between:
m.company.com company.com/mobile etc...
m.company.com is a preferable and relatively common approach.
There's also company.mobi but if you really care about users, then cater for every permutation that users could try...
company.com/mobile [404's should always be handled by all your domains, so directory's don't count here]