The tax policy still isn't crystal clear to me, but I think you are asking if the $250k (it is actually $200k for individuals) applies to income, or earnings. This is one aspect I'm still not sure of.
However, dividends, capital gains etc are considered earnings, not income. I saw the numbers awhile ago (can't find it at the moment) that to be in the top 5% of incomes, one would have to make around this $200k threshold. To be in the top 5% of earnings, one would have to earn about $600k.
Since Obama keeps saying 5% of people will be over the income threshold, based on the data I mentioned above, I have to assume that he is talking income. If this is the case, then as I said, people like Buffet, Gates, Brin, Page etc, who don't have salaries, may not be affected as much.