Publius, while accepting the validity of grievances against the frequently sexist coverage of her campaign, tries to make the case against Clinton. To me, #1 remains the most persuasive. I think Obama might have a marginally more progressive domestic policy, but the differences are narrow enough that this could be mistaken. But it's hard for me to get around the fact that Clinton completely botched the most important issue of the Bush era. (Moreover, I'm not willing to assume that her vote for the war was an "insincere political gamble;" that's possible, but I think we have to accept the possibility that she voted for the war because she supported the war.) See also Ann on this issue.
And her pro-war vote is not merely problematic on the merits; it's also bad politics. On the "Clinton electability" issue, as Ygelsias says, Drum is narrowly right but takes on only the weakest version of the argument. I have never argued that Clinton is "unelectable," and it's likely that the structural conditions in November will make any Democratic candidate a favorite over any Republican. But this doesn't mean that Clinton/McCain isn't the worst plausible matchup for the Democrats. And even assuming that head-to-head polls aren't useful at this point, the fact that Clinton took the Republican position on the most important issue and hence will not be able to exploit an issue that should favor the Dems will surely be a problem.
And there are a variety of other areas in which Obama has more upside. Obama has the ability to mobilize voters who generally turn out in relatively smaller numbers, while Clinton's core constituency (older women) already votes at disproportionately high levels. And while we don't know for certain that Obama's lower negatives and favorable media coverage will hold up, the worst that can happen is dropping to Clinton's levels. (And I'm not arguing that conservatives won't attack Obama; the question is how much right-wing critiques will penetrate the mainstream media and swing voters.)
Now, if you want to argue that if a candidate can win a primary, "electability" is just too unpredictable a factor to be meaningful, that's fair enough; but I don't really see a good progressive case for Clinton on the merits either.
--Scott Lemieux