It aggressively reinstalls any time you run Google Play, and on my phone, whenever the phone is turned on, Google Play starts up just to download the damn thing... so I rolled back to the (now useless) hardware version of "Market" to solve that problem. Another option is to boot the phone with WiFi and Data turned off, then terminate the Google Play app as well as any update-related aps.
But when you consider Google makes the OS itself, all this really does besides waste your space, is save them (and you, if you aren't unlimited) a ton of bandwidth. Not nearly as much bandwidth as you'd save simply NOT HAVING ANNOYING ADS in the first place, but, greed knows no bounds, even in the open source community this advertising pollution is forced on users. Oh well.
What is it? It's basically a 3166208 byte version of G+ just for aps...
600k of PNG files
232k of XML files
1356k in "classes.dex"
890k in "resources.arsc"
and some licenses
resources.arsc has some binary stuff up front, and is cram packed with text in every language known to mankind. They really could have saved half a meg by simply only including the license/instructions/etc in the language relevant to the user; this bloated approach is a standard software-industry tactic to eventually force hardware upgrades (and related embedded software "sales" via manufacturers - all the crap many of you rooted to get rid of in the first place. lovely!)
the classes.dex file is apparently a big ole bunch of java-based extensions for getting your identity from google for enabled aps, showing ads, hitting google analytics servers, that sort of thing.
Oh, and there's an Apache user license in there too:
Basically, Google just jacked 2% of your 160meg partition so they can show you ads faster & cheaper. Think it will be enough to offset that miserable third quarter report? Doubt it!
google earnings - Bing News
Owning Google hardware has given me a new appreciation for the accuracy of bing search results... which generally suck, but seem far more accurate on this particular subject :-)