One of the best parts about updates inside the Play Store for apps is that we can see what's new. As a geek, this is something that is fairly important as we can learn what the differences are between a previous release and the currently update build. This might not be important to some but it's great that the devs and Google want to keep us users in the know for the changes that have been made. All of this information can be found in the What's New section of an apps description when you're surfing the Play Store, and is usually the first thing you'll see when you tap on that app.
More than being important from the end user side of things, changelogs are something that can be a very useful tool for developers, as it lets them explain the changes that have been made to their users. Its great that we can be informed about the changes, but it's even greater for the devs so they can show people how things have been improved, tweaked, fixed, etc. Without these changelogs we might never know how an app has evolved after an update is released. As of today, developers can now make it so that the what's new section can show changes for the different version of the app that they might have, I.E. alpha, beta, and final builds. Google announced these changes this morning on the Android Developers blog.
What this all means is that basically developers can now have separate bits of text for each individual version of the app, and relay those in a relevant manner to the right groups of people. For an example on the user end of things, when you opt in to a beta for a specific app through a google+ community, any time you go in to the Play Store to update it, you will see potentially different text in the what's new section than someone who might have a final release or an alpha build version of the app. This will allow us to see more relevant information to what we're using, as opposed to a general set of descriptions.