There's an unsurprising correlation between developers that respond to reviews and the average ratings on their apps. Apps with a higher number of responses often have above average ratings, especially when they can turn an unhappy user from 1 star to 5 stars with a helpful tip. Sure, there are exceptions, especially if the responses are combative, but a few simple words can turn around the angriest of customers.
Google added the ability to reply to reviews for a limited number of developers almost four years ago, then opened it up to everybody about a year later, but replies always had to be done through the interface of the Google Play Developer Console. There's now a new Reply to Reviews API that allows third-party systems to post responses and automate the process.
The brand new Google Play Developer Console app is already using the Reply to Reviews API so developers can respond to users right from their mobile devices. Google also partnered up with two popular customer support systems, Zendesk and Conversocial, so developers on those platforms can immediately take advantage of the new capability.
For developers that want to build their own custom applications to interact with customer reviews, check out the API documentation.