Tom Vilsack, We Hardly Knew Ye
1) If your name is "Vilsack," you start in electoral politics with a large disadvantage. Kudos to the former Governor for advancing as far as he did. (No, I don't have a good explanation for why "Obama" is less of a handicap. It just is, somehow.)
2) The favorite son phenomenon is basically a thing of the past. Remember 1992, when Iowa Senator Tom Harkin won the Iowa caucuses because the other candidates didn't bother to campaign there? Remember how Harkin's campaign completely fizzled afterwards? This should have been a clue to Vilsack that he was doomed from the start: Had he won in his home state, the victory would have been dismissed in the way that Harkin's was; had he lost, that would have been proof positive that his campaign was DOA.
3) There may be no logical stopping point to the ever-earlier start of the Presidential campaign. Vilsack quit because he couldn't raise serious money, given the crowded field. Partly that was due to domination by more charismatic candidates (read Obama) who didn't start any earlier than he did, but it was also partly due to the fact that other leading candidates started their fundraising campaigns much earlier. John Edwards has been running more or less since election day 04, and Hilary Clinton has been running more or less since election day 2000 (some might even say earlier). To the extent that the fundraising drives the schedule, even sensible reforms in the primary schedule (of the sort urged here by my co-blogger Craig Albert) won't affect the start date of the race (although they could affect who among the survivors of the "money primary" wins the actual nomination). Campaign finance reform could alter the dynamic, but it would likely take reforms too strong for the Supreme Court to uphold. Bottom Line: Jenna Bush and Chelsea Clinton should get started raising funds for their 2028 runs asap.