Yes, this is big news for SFO. It means that roughly 75% of the gates -- United, Alaska, Delta and Star Alliance international carriers -- are now connected airside. It should help lots of folks make tight connections they otherwise would have missed.

The other airside zone is International - A and Terminal 1 - Harvey Milk (airside corridor connecting them). You'll need to re-clear security if you want to visit the Centurion Lounge if you're flying out of this zone. I don't think it's worth the walk and the time. Amex cardholders with Priority Pass have access to the Air France lounge, which is right at the end of the airside corridor at the entrance to International-A.

Current Air France Lounge access times for Priority Pass cardholders: Monday: 07:30 - 16:30 Tuesday: 07:30 - 23:30 Wednesday: 07:30 - 23:30 Thursday: 07:30 - 23:30 Friday: 07:30 - 23:30 Saturday: 07:30 - 16:30 Sunday: 07:30 - 23:30 Note: Hours may vary according to flight schedules. Access may be restricted between 11:00 - 15:00 daily due to space constraints.