Short-term capital gains will be 15% (Fed) + 5% (Fed Increase in 2011) + 3.8% (this) + 10.3% (California). 34.1% capital gains!
This does not compare favorably to anywhere else in the world. For a CA startup founder, capital gains are going to be 1.5-3x higher than most countries.
This is an issue primarily because (half?) of US startups are founded by immigrants. At some point, it becomes more attractive for an immigrant to go to Vancouver, BC (21.5% tax rate, much easier immigration process, better quality of life than SFBA) or even to remain in India or China. The tax advantages might also push for Hong Kong or Singapore startups, with 0% capital gains and very low income tax.
A big number minus 34.1% is still better for an exit than a much smaller number minus a small percentage, but California is definitely not the only place to do a startup.