I've got two pieces of advice for Gen Y as it enters the workforce. I'll convey them using the words of much wiser men.
First, Voltaire on digital oversharing: "The secret of being a bore is to say everything." A good ground rule, I believe, is to primarily use an enterprise's 2.0 platforms to share information that passes a simple test: would a coworker I've never met find this professionally interesting?
Second, Goethe on the difference between how people in companies should act, and how they actually do: "a confusion of the real with the ideal never goes unpunished." The advice here for new Gen Y workers is to understand the political and organizational lay of the land before engaging in egalitarian online interactions and fearless truth telling. You may well decide that you'll take the consequences, but you should first be aware of what the consequences are. Confusion here is not likely to go unpunished.