I'm almost enough of a political nerd and devloper nerd to try this, but I think the hardest part would be the scraping... Since the news sites have probably changed their formatting since the last election, it would be hard to test the results until they start displaying. If it take an hour to get all the bugs worked out in the scraper, well by then, the scraping might be usless. Maybe there's some kind of centralized API for accessing raw election results, though.
I'll bet you could get each state's official SOS results relatively easily. However, "calling" the election depends on more than just the official SOS reports. CNN will call things when their exit polls show one thing and then the early rounds of official results confirm them.
I think county by county results would be enough to do a reasonable prediction but I don't think SOS websites are updated with those results in anything close to real time on election night.
