Everywhere, the media is reporting "ten point victory", but you do the math. It's 8.6 points!
... which is pretty okay, really, given that the Obama campaign expected to lose Pennsylvania based on its demographics, according to a spreadsheet that was previously leaked to a website.
Ultimately, Pennsylvania was about expectations and momentum for the Clinton campaign while for the Obama campaign it was all about keeping a very ugly contest close, allowing for further attrition that would lead them towards the goal of 2,025 delegates.
While Hillary Clinton's campaign closed their ~140 delegate gap somewhat, they face a much more serious challenge, because after tonight, they find themselves needing nearly two delegates for every one that Obama needs to win... and that ratio will only get uglier after Guam, North Carolina, and Indiana.
By not losing badly tonight, the Obama campaign dodged the last big bullet, and put themselves considerably closer to victory. It's not clear how, if at all, the superdelegates will respond, but I don't suspect it will effect things all that much, or make the kind of argument that Hillary Clinton would like to make about Obama not being electable.
Next stop, Guam! ... which should be an easy Obama pick-up, I suspect, based on Obama's connections with Hawaii.