Originally Posted by jsloan

Correct -- the flights that I'd expect someone to take would be something like BOS-EWR-TYO / TYO-PEK-ORD-BOS or whatever.

And, yes, the extra time is for delays at PEK. You'd have no problem with the TWOV if you're not planning to leave the airport; there's an international connection line that you'd take and show your passport and boarding pass (assuming you're traveling on a passport that's PRC TWOV eligible, including the US). If you are planning to leave the airport, you should still not have any problems with the TWOV, but I'd be prepared with everything printed out including your Beijing-area hotel and return itinerary.