Nieman Watchdog's Dan Froomkin on the failings of the media's factchecking:
Then there's the fact that most fact-checkers feel obliged to provide balance, citing both side for misstatements even if they aren't vaguely in the same league – and even if some didn't actually come from the campaign. This creates a bizarre incentive system: If you're going to lie, you may as well make it a real whopper. Similarly, after it's been said once, there's no incentive not to keep saying it. Chances are, you'll only get zinged for it at most once per news outlet – even if you repeat it over and over again, long after it's been firmly "rebutted." In fact, it may well sneak back into the coverage, the rebuttal entirely forgotten.
So what's our alternative? Well, one alternative would be to fight back – for the press to create some sort of hugely negative consequence for making stuff up. For instance, to make it the lede of the main story every time a candidate repeats an obviously untrue statement, rather than a one-time-only sidebar deep inside the paper or newscast. But my ever-triangulating colleagues in the media are loathe to do something that makes it look like we're taking sides, even if that side is accuracy.
Froomkin has ideas about how his colleagues should proceed; take a look.