Its basically the area around and including San Jose, I pass through there everytime I go to San Francisco. I'm not sure about Tech Heaven, but its the most technologically ahead place in the country. A lot the major business' headquarters are based there, a lot of the RnD labs are over there, so if you're looking for the latest and greatest, its either there, or over in MIT in Boston.
It doesn't have any impact at all on the regular lifestyle of the people though. Silicon Valley is just a term businesspeople gave it, cuz some of their manufacturing plants are there too. I know Xerox PARC (Palo Alto Research Center) is there, its the birthplace of a lot of new technologies. Also, the Institute where nanotechnology is being invented is in Silicon Valley.
Still no impact on the regular lifestyle...maybe the schools.
I hear Japan is the Tech Heaven these days.
I'm partial to MIT (Massachussets Institute of Technology).