If you aren't familiar with terms such as "Airpush" and "SellARing," they are two "innovative" ad networks that allow developers to generate revenue from their apps by either sending you ads in your notification bar (Airpush) or by replacing the ringing sound you hear from the other end when you place a call with a 10-second ad (SellARing) (thanks, Android Police). Google now reserves the right to ban apps that employ these insidious revenue-generating methods. While the changes don't specifically mention those two ad networks, the policy does forbid apps that "simulate or impersonate system notifications or warnings," or "make changes to the functioning of the user’s device outside the ad."
Also on the chopping block are apps whose icons or names resemble other apps closely enough that it could confuse users (this applies especially to those that resemble Google apps or system apps). For example, you rooted users, imagine having a gapps package that doesn't include YouTube or Google Talk, so you go to the Play Store to install them manually. Meanwhile, some developer has posted a third-party messaging client simply called Talk that features an icon similar to the Google Talk icon, and you unwittingly download it, thinking it's the Google app (as I'm sure you know, there's no lack of third-party messaging apps available). This type of scenario is exactly what the updated policy is designed to prevent.
Now the ball is in the developers' court, to either comply with the new requirements within 30 days or have their apps pulled from the Play Store. Of course, many of you install your apps from outside sources such as the Amazon App Store, or lesser-utilized sites such as GetJar, so you would still be subject to the possibility of downloading apps that include annoying spamware as in the examples mentioned previously. If that is the case for you, and you're rooted, I would recommend flashing a Jelly Bean ROM that gives you the ability to disable notifications on a per-app basis by opening App Info (pictured below).
(1) drag icon from app drawer to "App Info" box on top of screen, (2) clear the "show notifications" checkbox