See Glenn Greenwald for the conclusion to this sad journalism chapter. But basically, Rosen wrote a wildly irresponsible hit piece on Judge Sonia Sotomayor prior to her nomination pick--a piece that relied on anonymous sources who trafficked in nasty gossip and a piece in which Rosen admitted he hadn't had time to examine Sotomayor's work in detail--and now he says well, he was just blogging and he'll never do that again.
Y'know blogging, where ordinary standards of fairness do not apply and where you can just post whatever scraps of unconfirmed misinformation you find laying around. Y'know, blogging.
The excuse that Rosen was merely "blogging" is, just as a factual matter, so obviously false: his Sotomayor piece wasn't on any of the TNR "blogs" (as happens when Rosen is actually "blogging") but instead was presented as a stand-alone article; it was, as NPR notes, "more than 1,000 words"; and TNR touted it as "the first in a series of reports by TNR legal affairs editor Jeffrey Rosen about the strengths and weaknesses of the leading candidates." Does that remotely sound as though they intended it to be a "mere blog post"?