Aside from forestalling one (of many) avenues of legal attack, this is all good. Accountability always is.
One of two things are happening: Either Pelosi thinks she has enough votes to pass the bill; she is waiting only until after the President's "pep rally" to Democrats to schedule a time for tomorrow's vote, in order to promote the perception that Obama succeeded in rallying the last few undecideds to his side.
Or, more optimistically, Pelosi could have a "Rubik's cube" disaster on her hands -- every effort to win more votes are losing her others, and she decided that she could win over more votes by abandoning deem 'n pass than by keeping it.
One wonders how those who went on the record for "yes" when they didn't think they'd be subjected to an "up or down vote" on the Senate bill are feeling now . . . It takes away their last fig leaf of deniability on whether they supported the Senate version of the bill -- and rushed to do it before the costs imposed on future generations could be calculated and considered.