You can add location information to your Tweets, such as your city or precise location, from the web and via third-party applications. You always have the option to delete your Tweet location history. Learn more
I really think this is going to bloom in the next few years. A lot of companies have started putting people on this internally ("we want to spend $xM or xxM on this, where do we put the money?") just in the last year
A big problem is connecting funding to researchers via grantmaking that doesn't reward stupid hoop-jumping and outright deception, but having met some of the people who've started working on the business side I think the level of competency is much higher than one might expect
