fssfThank Twitter. Thank Ed Lee. Thank Ron Conway.

It's official. The Four Seasons on Market Street in San Francisco has become San Francisco's answer to the Rosewood. Pando's office is a few blocks away, and every time I've gone for lunch there of late, it's like walking into a tech founder social club. A few weeks ago I stumbled across a clandestine meeting between Steven Spielberg and several tech luminaries aimed at keeping George Lucas's proposed museum in the Bay Area.

Today, it was a Citibank sponsored meeting with Rakuten founder Hiroshi Mikitani, that sported an eclectic group of about 20 CEOs including HotelTonight's Sam Shank, Etsy's Chad Dickerson, and Lucas Duplan from the riding-not-so-high Clinkle. (Astoundingly, we're told, it was Duplan who left halfway through the presentation, presumably having learned everything he could.)

During lunch, I even overheard this gem: "I'm going to close this round, and then I'll grow some balls." If that isn't modern tech entrepreneurship in a nutshell (pun intended) I don't know what is.

The center of gravity in the tech world has moved from the SOMA area to mid-market, thanks to Mayor Ed Lee's tax breaks and incentives. Depending on who you talk to, it has brought economic clout into the city's long most-blighted area or has set off a wave of atrocious gentrification.

But unlike SOMA's techsplosion which was slow growing as Web 2.0 got going, the mid-market techsplosion was rapid. Square, Twitter, Zendesk, Spotify, HotelTonight and dozens of others are moved in en masse with combined tens of thousands of employees.

And there are very few fancy places to go to lunch with an investor, with Steven Spielberg or… a Japanese billionaire. So, at least until the restaurant opens at the bottom of the Twitter building, the Four Seasons has become it.