There is the Ubuntu Developer Summit (where Qt Project is involved with sessions and sponsorship) and there is also the Tizen conference, overlapping some days and few BART stops away in San Francisco. There will be some Qt visitors around and we want to show them hospitality with some dinner and drinks.
UPDATE: location decided. Grumpy's (http://grumpyspub.com/) is a pub where we can eat & drink, sit or stand up. They don't take reservations. Happy hours between 5-7pm. The 5:30pm is just a concept ;) - you can come and leave at any time. Just look for the Qt / FLOSS shirts and wear one yourself (if possible) for easy identification.