I'm not really going to wade in, although I do come down on the "it's nonsense" side, but I did want to quote this one passage:
CalPundit is also too fair to the Bell Curve. The book contained more than just deliberately shoddy science - which should be warning bells enough - it also was an explicitly racist tract by intent and design. Every time I refer disparagingly to the Bell Curve some true believer expects me to write a 50,000 word critique of the book to justify my opinion of it. Frankly, it's as if every time I spoke disparagingly of The Protocols of the Elders of Zion someone expected me to write a 50,000 word critique of it. The Bell Curve has been "Fisked" by researchers in every field, and it is not, as Charles Murtaugh suggested, being part of a herd mentality to have concluded that it is, to a great degree, a load of explicitly racist crap. Glenn Loury rightly abandoned his old pals after their enthusiastic embrace and promotion of those twin books of pornography for closet racists - The Bell Curve and The End of Racism.Atrios goes on to bring up examples of borderline racism within the text, but that's not really important. What grabbed me was the general problem: that every time an idea of phenomenon that has been thoroughly and scientifically discredited is brought up as discredited, inevitably it prompts the sort of response Atrios mentioned.
It's actually a fairly effective technique. It decreases the S/N ratio of any commentator it's aimed at, because he or she must spend insane amounts of time refuting these assertions, and sometimes the refutation of a simple assertion can be relatively complex: witness the conflict of evolutionary science vs. creationism. It can win over people who don't know the truth, because there is (I believe) a natural human desire for a simple and understandable answer- such as "intelligence is a function of race", instead of a complex and difficult answer- such as "IQ is the function of a blizzard of different influences, of which genetics is only one... and race is such a baggage-laden concept that it's damned near useless". It can also prey on the desire of people to be "fairminded", because giving equal time to two people will privilege the one spouting a whole bunch of simplistic attacks- the person with the more complex answer simply doesn't have the time to deal with it, because the answers take longer than the questions.
(Note that this has nothing to do with the left/right divide; leftists spout simple and easy answers too. My lack of sympathy towards Marxism has a lot to do with it's underlying "easy answers" of class conflict, the labor theory of value and the necessity of revolutionary change.)
This also remains one of the reasons why blogs are a dangerous medium. Blogs can and do take advantage of "network effects" of ideas; ideas are repeated and built up by bloggers linking to each other, commenting on each other, etc. When the ideas are critically analyzed (or are based on critical analysis) that isn't necessarily a problem, but too often (as in real life) they're passed on unquestioned and uncriticized. This is especially a problem for blogs because of the emphasis on brevity; ideas tend to get passed around in their simplest form, and are usually discussed based on that understanding. Even complex answers to simple assertions can (and usually are) boiled down to a few key points, with those points being no stronger than what they're rebutting and, thus, easily ignored by those who would prefer to agree with the former point. (What is usually "boiled out" is the underlying analysis that makes the rebuttal superior in the first place.) So blogging can be a problem.
The other problem, however, has nothing to do with the blogosphere. It's quite simple: the Internet and Academe are by and large seperate entities. This creates huge problems, at least from my experience. There are a *lot* of political and economic issues that get discussed in both, but while academics can draw on, say, a blogger (although they probably wouldn't), the same is not true in the other direction. You can't hyperlink to a journal; even where such links exist, the general public doesn't have access to them. At best you can do a citation, but citation of material without linking isn't exactly convincing online. Besides, there's another problem with doing that: those who have an agenda (or the cash) can easily make their material available online, and opposing or underpinning material would be ignored. So you might be able to get some position papers or even published stuff from, say, Heritage or AEI or the Sierra club (which are in the business of influencing public opinion), but you'll never get that brilliant grad student paper that was published in a political or economics journal that conclusively refutes what Heritage is saying... and even if someone finds it, they can't link to it, and readers aren't going to pay attention. (If the blogger or commentator or whatever even has access to it; while many bloggers are academics, most people aren't.)
(I ran into this myself a little while ago when discussing appeasement... there was a good paper using game theory to defend the idea of appeasement, but it was never something I could link to, and an un-linkable document in the face of reams of assertions that appeasement *must* lead to a WWII scenario isn't very useful.)
Plus, it furthers the disconnect between Academia and the general public, who never get to see what the hell these guys are working on. All they get is third- and fourth-hand impressions, usually from people who have an agenda.
I'm not quite sure how to solve this; it gets into the problem of journals costing so damned much and how that indirectly hurts both the natural and social sciences, but the reality that those who write papers need to be compensated and that advertising will simply not do. Suffice it to say, though, that it severely influences the type of information available to the public, and the wealth of (suspect) information available online only makes it worse, because it makes it seem like it's not an issue. And it makes the continuing popularity of works like The Bell Curve possible, because of assertions that the public always sees and refutations that they don't.