The point is being missed here: when the press is in the tank for a candidate and is not fair and balanced, everyone loses.
This case is pretty benign compared to some of the other issues for which the press has been "in the tank" for the past few decades. The media have had 20 years to report on unsustainable budget deficits, the massive Social Security and Medicare shortfalls we're on target towards realizing by 2020, human-induced climate change, the PATRIOT Act, warrantless wiretapping, and other defining issues and have at best paid lip service to them. And the most glaring example of the press being asleep at the wheel (or worse yet, intentionally taking their eyes off the road) has been the leadup to U.S. military involvement in Iraq in 2002-03.
Perhaps if the views of Sen. Obama and other opponents had been better covered by the press before March 2003 we wouldn't invaded that country, or at least constructed a sounder policy and gathered more solid intelligence and used a better-considered strategy for an invasion. I remember virtually no coverage of Bush's opponents by the major media outlets leading up to the war. My reading of the mainstream media was that Bush had, in hand, evidence of Saddam Hussein's regime being in current possession of nuclear and biological weapons, or at the very least hard proof that he had the materials necessary to build them. Hindsight allows us to see that this the evidence was shaky at best that Hussein had any type of WMD since the end of the 1990-91 war. I understand the fact that in many cases this type of information needs to be classified, but all that the media would have needed latch on to an anti-war argument would be a public statement by a member of Congress or the Bush adminstration is "Based on the contents of the $Briefing_Name classified briefing, I do not feel that we currently have justification to initiate hostilities in Iraq." I'm sure such statements to that effect were made, but media coverage downplayed these statements and these statements did not lead to very many follow-up stories.
In the 1970s, the press was vital to uncovering the Watergate scandal and pressuring Congress to pass reforms in its wake. If President Bush or President-elect Obama were found to have engaged in similar behavior, I'm not at all convinced it would even make a big story these days. Unless the scandal involves sex or drugs, the media now tend to downplay stories involving political figures and other notable people (and when sex and drugs are involved, the story is often blown up out of proportion). I don't know what's changed since then. Is it the fact that now entertainment content and journalism are more closely tied together in the corporate world then they were 30 years ago?
I'm not sure what agenda the press has, but journalists used to feel a responsibility to tell a story how it is and give it the importance it deserves (i.e. putting it at the top of the front page or on the bottom-right corner of Page B14 as the story dictates). Sure, TV ratings and circulation numbers have always been important, but now it seems to be the only factor. As you've put it, the press has been "in the tank" for some time.