I'm hoping for another humdinger but I fear tonight could be a tame affair. Hillary has to play fairly nice given the backlash against her campaign's bare-knuckled tactics of late. And Obama has mad momentum that he can afford to coast on, no?
That said, today the Clinton camp is still pressing the theme that it's Obama who has been running a nasty and negative campaign. Today it sent out a memo contrasting a fall 2007 Obama assertion--that he only hits Hillary on substance--against a string of shots his campaign has taken at her character, i.e. that she is calculating, untrustworthy, and polarizing (although I'm not certain that last one is personal, per se).
Tonight Hillary's best offense may be a kind of defensive cry that Obama is playing nasty and getting away with it. That's certainly what her campaign insists is the case.