It's not very often that the political world is genuinely surprised. With such huge political operations, media organisations and advertising agencies leaks are virtually impossible to prevent.
It is true that Barack Obama kept a tight lid on his VP pick, but Joe Biden had been regarded as the front runner for weeks and the final announcement was made at 3am after CNN broke the story shortly after midnight on the morning of 23rd August.
But I think it is safe to say that the political world - from the blogosphere to the established order of Fox and CNN have been taken back by this announcement.
Much of the speculation up until the early hours (ET) of this morning remained focused around Mitt Romney, Tim Pawlenty and even Joe Lieberman. A number of sources had even taken Gov. Palin's name out of consideration after it was 'revealed' she would not be present in Ohio today.
Rumours only began to surface after an eagle eyed airport worker reported that a middle aged woman had been whisked under the cover of darkness through an Ohio airport with her two teenage sons.
What remains to be seen is the reaction that the announcement will provoke.