Mobile marketing for earned and owned communications is something I am working hard to get my brain around. I envision lots of ideas but not many of a practical nature. This week's "Friday Five" from PRSA is dedicated to current happenings in mobile marketing. It offers a nice instant survey of current events (successes and works-in-progress) and gave me . I'm only beginning my thinking here but it seems to me that, done well, mobile could be a rich engagement medium...or it could be an utter nuisance. Who are the mobile marketing gurus -- the industry leaders with serious credibility? Have any individuals or organizations emerged with credible strategic advice and best-practices? Are there any compelling case histories that show how mobile can be effectively integrated into marketing? Where's the best data? Who do you trust? I'd welcome all your suggestions on the topic.