Amazingly, the Obama administration is seeking to punish the practice of investigative journalism. To the excellent post by Katie below, I'd add this quote from the WaPo story:
[In court documents, FBI agent Reginald] Reyes wrote that there was evidence Rosen had broken the law, “at the very least, either as an aider, abettor and/or co-conspirator.” That fact distinguishes his case from the probe of the AP, in which the news organization is not the likely target.
In other words, the administration is alleging that Rosen somehow broke the law simply by soliciting information for publication. What this means is that every investigative journalist could be in legal peril every time s/he sought information that turned out, in an administration's view, to threaten national security. Imagine the creative and selective enforcement an administration could employ to deter investigation of tis doings. This is what the First Amendment was designed to guard against, a point even the Post article concedes:
[I]t remains an open question whether it’s ever illegal, given the First Amendment’s protection of press freedom, for a reporter to solicit information. No reporter, including Rosen, has been prosecuted for doing so.
There is a good reason these sorts of accusations and prosecutions aren't thrown around often. A free press (and the Second Amendment) are a free people's only defenses against government tyranny. What's more, it isn't illegal to publish classified information (a protection for which the ObamaPhiles at The New York Times had reason to be grateful during the Bush administration -- but note that the Bush administration never went so far as to try to criminalize journalistic activity).
Oh, and keep in mind that this spying on and prosecution of Rosen was happening in 2009, at the same time that the White House was waging war on Fox News. Coincidence? You decide.