For US passport holder, TWOV is still good. We did just that this past week. One caution though: you must stay at the same hotel you declared on your arrival card. The public police at Shanghai apparently called my hotel to inquire if all of us indeed stayed at the hotel. We had three of us traveling together, and at check-in, the front desk people only took my passport copy( I presented all three at time of check-in). They later got really nervous when they got a call from police on this to check if all three of us are staying at the hotel. They called us multiple time to request us to give them copy of the other two passports.