Fantastic link. That's much more useful than TFA.
Zooming down from a national view to the valley is a perfect example of how that map is useful. CA as a whole shows up as about average nationally. Zoom in a little, and Santa Clara County is a bright spot pulling most of the weight for the whole state. Zoom in further, and you can identify the tech mini-corridors like the Sunnyvale/Cupertino/Mountain View triangle (software-heavy), the North 1st Street chunk (hardware heavy), and SOMA (the app-development heavy pit where VC money goes to die).