I say Clinton wins by 14%. Her flacks will push the idea that something major happened when in fact the dynamics of the PA race stayed the same thanks to the Clinton-McCain-Media tagteam vs. Obama. The day after the primary Obama will still have more delegates, more states, and more overall votes.
At the end of the day the only way Sen. Clinton can now win the nomination is to steal it. But I think she'll have a healthy double-digit win in PA.