On intrade Pawlenty and Romney have suddenly cratered while Palin has shot through the roof as a plane makes its way from Alaska to Ohio.
This looks like a high-risk gamble by McCain - perhaps a last-minute change of mind as he realises that playing safe with one of the boring Repub white men isn't going to be enough to counter what the Democrats just produced.
One very obvious point is that it totally blows away the criticism of "inexperience" as the Republicans' main attack on Obama, as Palin has considerably less than Obama.
It is certainly one bold pick, and I reckon it must be McCain's own rather than the Roveites'.