You raise an interesting point.
Didn't Gov. Palin recently meet (without much fanfare) with some Republican monied players at one of their houses for an "introduction and discussion"?
Perhaps there was a meeting of the minds to have Palin take the lead in decimating Democrats from Congress (the fastest way to halt the Obama marxist juggernaut) by using her popularity.
Then supporting her in a run for the presidency in 2012.
I think there was something in her speech about "this being in the works for awhile".
One thing came across loud and clear from her announcement, she is afraid and disgusted with what’s happening to our country under Obama and she will do everything she can to help stop it and get back to our Founder’s ideals.