I don't want to weigh in too deeply on the "what is a journalist?" debate. Jeff Jarvis has covered that enough. Maybe more important a question is, "what is journalism?" I tend to think that journalism is only a sensor and distribution methodology for disseminating information. Journalism is made necessary by imperfect information. In societies where there is imperfect information (due to the slow spread of news, limited access, oppression, etc) it makes sense to have a group of people practicing something called "journalism".
If journalism is basically a sensor and distribution methodology for a society with imperfect information, what happens when the information flow starts to move towards perfection? The United States , or any country for that matter, will never have perfect information, but in so many ways the information flow now is better than it was 10,20,50 years ago. Does this mean that the umbrella of "journalism" should now apply to all information sources that abide by the canons of journalism (responsibility, freedom, independence, truth, impartiality, fair play)? I think the answer is yes, which leads to two fundamental shifts in modern journalism:
1) Focus on analysis over the news. In the past, journalists controlled news and could get away with just presenting the facts. Look at any old newspaper, which often reads like a diary. Now, since news isn't the scarce resource, journalists now focus more on analysis. I tend to think of journalists today more as referees. For many things, I don't need an intermediary to tell me what happened, but for those close calls I still need someone to sort out the details.
2) Working with sources as opposed to against sources. I think journalists still need to maintain an adversarial relationship with some news makers to keep impartiality, but there are so many outlets for news makers to get their own news out (blogs, forums, press releases, etc) that journalists can't really afford to always work against them. For instance, it is ludicrous to think that a company in today's world would cede all news control to a journalist. Companies are going to use all means at their disposal to get out the news they want to get out. I don't have a good answer for how journalism incorporates these sources, but it is happening. The days of a journalist saying "whoa, that's my job" to someone outside of the established walls of the newsroom are over.