The city is already starting to update the parking meters with new signage stating Sunday parking will be enforced in the city from 12 Noon to 6PM.
But wait... before you start feeding coins into that meter, you should read the other side of the meter that says Sunday enforcement is effective January 1, 2012.
I took a picture of this meter on Portola, nearby the Round Table Pizza.
Why 12-4PM enforcement on Sundays? Local church leaders asked the city not to enforce prior to 12 so their members can attend church without fear of being ticketed. As for me, I can still score free parking before noon to get a haircut.
Also, the meter I looked at says the maximum amount of time you can feed a meter is double the time of the regular Monday-Friday maximum. I'm not sure if this 2X policy will be effective in neighborhoods with major parking problems (e.g. Noriega, Irving, and Clement).
Also, be aware that meters within the jurisdiction of the Port of San Francisco, including near Fisherman's Wharf operate 7 days a week, including holidays; so if it's Sunday and you are parked nearby the Famous Bushman, make sure to feed the meter.