Well, that didn't take long. Earlier today, we reported that Google was limiting the number of devices that can be deauthorized from your Google Music account. The official limit on Google Music devices was 10 active devices, with the proviso that up to 4 devices could be removed from your account every year. As of this moment, the Google Music help page still echoes this, but Google might be back pedaling.
The problem with any account-based music streaming service, from a corporate standpoint, is that end users are a shared password away from getting access to free media. Really, who hasn't shared their Netflix account once or twice? In an effort to prevent this kind of abuse, Google Music (likely at the request of the music labels) has instituted a cap on the number of devices you are allowed to deauthorize: Four.