Last week I began looking for tickets for the weekend NLDS series between the Nationals and the Atlanta Braves. The Braves of course were subsequently knocked out in the elimination Wild Card game against the St. Louis Cardinals and now the Nationals are playing the St Louis Cardinals in St. Louis. But in looking for tickets in Atlanta, I noticed that Atlanta has implemented Demand Based Pricing. You can read more here.
Here is a screenshot of the FAQs.
With large troves of data, I imagine most event ticketing will move to demand-based pricing.