If Palin wants to run in 2012, why not do exactly what she announced today? It's an enormous gamble - but it could be a shrewd one.
After all, she's freeing herself from the duties of the governorship. Now she can do her book, give speeches, travel the country and the world, campaign for others, meet people, get more educated on the issues - and without being criticized for neglecting her duties in Alaska. I suppose she'll take a hit for leaving the governorship early - but how much of one? She's probably accomplished most of what she was going to get done as governor, and is leaving a sympatico lieutenant governor in charge.
And haven't conservatives been lamenting the lack of a national leader? Well, now she'll try to be that. She may not succeed. Everything rests on her talents, and on her performance. She'll be under intense and hostile scrutiny, and she'll have to perform well.
All in all, it's going to be a high-wire act. The odds are against her pulling it off. But I wouldn't bet against it.