As much as we all rightly loathe Palin and want to see her paper candidacy shredded, the least useful thing Biden can do in the debate is to waste time attacking Palin. I think Obama and Biden know that, and they will use the debate opportunity to go after WcCain. This memo isn't to them. It's to those of us who think Obama missed an opportunity to attack WcCain at the debate, and to those who worry that the moderator may not tear down Palin enough.
Many of us partisans, including me, were asking why Obama had to agree so much with WcCain and didn't spend more time tearing him down. Well, the reaction of the people who mattered - the undecided - by 2 to 1 paid off for him on that. But here is the other part of that: Obama didn't do the tearing because Biden will. Biden is more suited to that, and devastatingly effective. By treating Obama like an uppity kid, last week, WcCain gained the banner of the asshole, and set himself up for just retribution in many people's eyes. Biden will be more charming in attacking him than WcCain was at any point in his public appearances.
Consider that Palin's fav/unfav ratings per the DailyKos poll of today were 41/52, well in negative territory, and have been for some time. Palin has been hemorraging consensus everywhere but the diehardest limbaughoholics. She won't bring a single net vote to WcCain, quite probably the opposite. Attacking her is unnecessary, and may be counterproductive. She doesn't need Biden's help to fall apart.
Many of us worry that Palin will cry or in some way made to look like the victim of a sexist bully. Nothing takes care of that better than not to go after her, go after WcCain instead, and knock her down in the process. Palin can't defend WcCain. She can't follow Biden on that terrain. Her bookish neocon crammed 'knowledge' will not help. Just consider that while Biden has worked alongside WcCain for decades in the U.S. Senate, Palin hasn't even met with him outiside of the context of this campaign.
All Palin she can do is to attack Obama with slogans and generalities, but that failed WcCain, already, and will fail her. On top of that, she has to prove that she herself is presidential material, and if she spends time defending WcCain or attacking Obama, she can't do that.
In conclusion, let's be scream at the candidates and the moderator tomorrow, and throw shoes at the tv all we want tomorrow night, but let's remember also that the debates are not boxing matches, they are a very good way to get votes, even when the adversary isn't skewered.