Im hoping for a McCain-Guiliani ticket, with McCain as President. But I would vote for it still if Guiliani was the Presidential candidate.
Colin Powell, even out of his own accord would not run for president, because it has been presented to him before. He stated he is not a politician, he's a statesman. And if you monitor his last weeks into his term on the Bush Administration, he expended all the political influence that his name held both in America for the United Nations presentation, and against particular voting groups as he laid down unjust international laws in the State department days before he resigned.
Condi Rice does not seem interested, but she is a very likeable person with strong character. Most of the political turns America has been focused on complement her expertise with Russia and now China. Im positive that the nuclear talks with India is her strategy. She knows her stuff.
Hilary Clinton is losing her allure quickly. At one time I had thought about voting for her, but then as I watched her positions unfold on the US Senate, its not mainstream enough nor reasonable enough to represent the American people. She might follow the line of US Senators not to win a Presidency, unless she surprises us with some great enlightenment.