According to Dr. White, it is a variant of the California Ale Yeast strain they've been developing for 3-4 years. It is not from a commercial or local brewery and is named "San Diego" because it was introduced at the homebrewers conference there. It is supposedly similar, but complimentary to the California strain. It is clean, neutral, ferments high gravities, and not overly estery.
That being said, has anyone used it? My concern is the narrow temp range as one could start it at 65F and a high gravity, rapid fermentation could easily boost the temperature well above 68F. Anyone push either end of this one yet?
WLP090
Optimal Fermentation Temperature: 65-68F
Attenuation: 76-83% +
Flocculation: Medium-High
Alcohol Tolerance: High
WLP001
Optimum Fermentation Temperature: 68-73°F
Attenuation: 73-80%
Flocculation: Medium
Alcohol Tolerance: High