Is this about Facebook? As that social network may say in a status update, "it's complicated."
Google's new Play store version 4.0.27 has some extra language in its policy section under "Dangerous Products." It notes that:
An app downloaded from Google Play may not modify, replace or update its own APK binary code using any method other than Google Play's update mechanism.
Essentially this means that once an app is downloaded by an Android user it cannot contact home base and auto-update its own operating code. Instead, it has to use the official Google-approved channel. In terms of malicious apps that at first seem to do one thing, then sneakily update to violate user privacy or some other wicked act, this makes great sense. But as Engadget notes, the move will not impact the majority of apps because they all already use Google's own systems. Apart, that is, from Facebook. It recently changed its Android app so it could automatically update without Google having oversight.
The move may be a political one directed against Facebook which, from some viewpoints, may be trying to subvert the Android experience with its Home front end. But Facebook and Google say they're great friends. So this really is complicated.