Not that I agree with patrickzgill's evidence-less assertions, but in his scenario, the fabricated votes wouldn't be the percentage over 100%, but the percentage over the real turnout rate (which might be 70% or so).
That's true. I was assuming he meant 8% OVER expected turnout, since 108% turnout is frankly ridiculous. That's one of the problems when people don't cite anything we have to assume what the numbers mean.
Taking a more nuanced view, one way the numbers could be true is by people voting in specific precincts that they don't live in. I.E. they go to the polling place near work not home. Which would just mean that one PA vote is counted in a different part of the state, not actually affecting the outcome.
States have different rules governing this kind of thing and I have no idea what the laws in PA are like.
Philly county has 644,768 total votes currently with close to 100% reporting.
10% rather than 8% of that total is (generously) 65,000
Current lead for Obama in PA? 284,000 votes
So even if we amplify your 8% claim to 10% and over-round it is still not even close to making a difference.
Also if you are going to make claims about such contentious things it would be nice to cite some source.
My numbers above come from google's election results site
http://www.google.com/elections/ed/us/results