To add to the confusion different websites are reporting conflicting estimates in what to look for in early returns
FiveThirtyEight.com says rural votes will be reporting first and a likely Clinton lead:
"(2) Very early returns, such as in the first hour after polls close. Because there are such profound regional differences in the way that Pennsylvania polls, the results will be almost entirely a function of where the numbers are coming in from. Odds are that rural areas will report their results before the cities, which means that the early numbers should favor Clinton (this may actually be a nontrivial advantage to her in terms of media narrative; the race could very easily be called for her when the ticker shows Clinton ahead by 14, but things could close to within 8 points once all votes were counted)."
http://www.fivethirtyeight.com/2008/04/pennsylvania-scorecard.htmlBut Politico is looking at an early Obama lead 'cause cities and 'burbs will report first:
"Don’t be fooled by early results. The cities and suburbs usually report their returns first, which gives the candidate favored in those areas a quick – and sometimes fleeting – lead. The conservative-leaning small towns through the center of the state usually filter in much later in the evening.
This tendency has wreaked havoc in past elections: A Democrat goes to bed thinking he or she is the winner, but wakes up the loser. The last time it happened was 2004, when the Associated Press called the state attorney general race for Democrat James Eisenhower and retracted it later in the night as the numbers closed. Some newspapers went to print with the wrong results.So Obama could show a lead in the early results, but it might be short-lived. If Clinton is ahead at the start, she may never lose it."
http://www.politico.com/news/stories/0408/9772.html