I did a service call on a monumentally HUGE mansion (5 floors) off Mulholland Hwy in Hollywood Hills, built around the 1950's with a 3 phase 480V 1200A service. 3 elevators, enough A/C to have you singing "Oh Canada" in any weather, indoor pool, a jacuzzi on the roof, a computer mainframe room kept at about the same temp as your refrigerators salad drawer, and of all things, a bowling alley [Linked Image]

Other than that, the Governator has a ranch in Malibu Hills with 3phase 1600A at 208Y/120V.
Those are the only 3 phase houses I've actually "worked" on.. But I have come across a handfull with 400A 240V 1 phase..

Seems most of the new houses in "The OC" are 200A 240V single phase.

So Cal Edison has load requirements which must be met before they will even consider giving you 3 phase power whether you're commercial or resi. If you don't draw enough Kw/H to meet this after they give you the 3 phase service, they'll charge you for a "minimum demand" anyways, which last I heard landed you in the $800/month ballpark [Linked Image]