As has been reported by many, contrary to what he said as a candidate, President Barack Obama HATES whistleblowers. He hates them so much that his administration has prosecuted more of them than all previous administrations combined. Right now, his justice department is going full bore to convict Bradley Manning of "aiding and abetting the enemy" when all Manning actually did was to expose a plethora of government lies and potential war crimes.
So, it is rational to think the the POTUS is out of his mind in rage at the currently unknown whistleblower who passed top secret information on to Glenn Greenwald of The Guardian. Someone with a high level of access handed over a physical copy of the legal decision that grants the Obama administration the authority to compel Verizon (probably every other company in the industry too) to hand over all of its data about its customers to the National Security Agency.
You want to talk about an important leak? This ranks up there right next to the Pentagon Papers! As government leaks go, this is about as bad as it gets. It is embarrassing on a scale that is hard to fathom.
I am certain that Team Obama will spare no expense in trying to determine precisely who ratted them out and when they discover that person's identity, I certainly wouldn't want to be him or her. While prosecution is the most likely outcome -- I mean, we can't have people exposing the police state for what it truly is, can we? -- it wouldn't shock me at all if the POTUS decided to forgo the time-consuming work of bringing charges against the whistleblower and simply added their name to the "kill list."
For that matter, my hero Glenn Greenwald and the editors at The Guardian should be nervous as well. The CIA flies drones all over the place and, maybe, one will "accidentally" kill yet another American citizen (Greenwald is an American citizen, albeit one living abroad).