Twitter's elite staff work in plush surrounds and eat oysters and lamb chops, outside HQ (above) on the south-side of mid-Market Street is San Francisco's poorest neighborhood -- the Tenderloin. 

There was a recent hearing by the city of San Francisco where Twitter was asked what it had done for the community in return for about $22m in tax savings since 2011. Here's an excellent report by Justine Sharrock on Buzzfeed.

"... it gave away $60,000 in promoted tweets."

 I was walking to an event at Moscone and took a few pictures of the neighborhood. 

Not much has changed on Twitter's street that I've seen. There's not much chance for gentrification when all the workers stay inside and Twitter cleans their apartments, and washes their clothes, and feeds them for free. Competing with local services is the opposite of gentrification. For the young engineers it's great it's like being back at mom's, free food and clean laundry, and without having to deal with mom.