The basics here are of course critical thinking and source evaluation - good 19th century skills, it's just that kids have to start learning this stuff earlier nowadays and we have new tools to help us. It would be possible to lament the emergence of a world that requires these changes - wasn't it better when our main access to information was books, with their more rigourous editing process? Andrew Keen has built a whole career lamenting the disappearance of the 'gatekeeper'. He is mostly focused on news and culture, but the idea is valid everywhere: "Before", most of our media exposure was vetted by experts, so what you read in books, for example, you could mostly count on. "Now", any idiot with a modem can publish, so we all have to be our own gatekeepers about thousands of topics we are not experts on. (The Telegraph's technology blogs are a hotspot for the debate around 'gatekeepers'.)
What really got me thinking was a comment on Rheingold's post by someone called dogu4: "Questioning one's sources is useless, unless one is questioning oneself as well. Consider many of the supposedly irrefutable facts regarding human health just in the last decade or so". A seed in the back of my head suddenlty became a full-grown douglas fir. I must admit I think about Warren and Marshall a good deal. They are the two Australian scientists who in 1982 found good evidence to link stomach ulcers and h. pylori bacteria. Despite this connection first having been noticed in the 1890s, this finding went against several received truths of medicine and Warren and Marshall had trouble getting their findings accepted. It took well over a decade for the connection between bacteria and stomach ulers to be fully accepted.