I have a theory. I am no genius and have no special connections to either campaign or the DNC, so my theory is nothing more than my own interpretation of the same data available to all of us. In other words, if it seems implausible to you, please do not think "on the other hand, he might know something that I do not." I assure you, I know nothing more than you do, whoever you are.
I am, however, perplexed by the sight of a high-level Clinton surrogate floating a trial balloon concerning a unity ticket at a time when 1) Sen Clinton is obviously in such a weak state that such an overture cannot be understood as an invitation to a Clinton/Obama ticket and 2) Clinton is simultaneously still making arguments suggesting that she plans to beat Obama. This is a strange and paradoxical state of affairs. One does not ordinarily bid for the VP's slot by attacking the candidate with whom one hopes to run, and yet McAuliffe's "what a great idea" can hardly be seen as anything but a bid for just that. What is going on?
Here is my theory: Clinton wants to be president. This is hardly a shocking insight. If she did not want to be president, she would not have run. She is faced with a real difficulty in attaining that goal, however, by this point. It is clear that she will not win the nomination in 2008, and it equally clear that she would fare no better as a 3rd party candidate than any other 3rd party candidate has ever fared. As such, she has no realistic path left to the presidency in 2008.
2016, however, is a long ways off. Countless precedents have shown that her odds would be long if she were to wait those eight years (remember Dick Gephardt?). Far better if she could make another go of it in 2012. Much talk has been given to the idea that she is running so as to weaken him enough to ensure his loss this time around, so that she might run against McCain in 2012, but this is rather problematic. She would alienate a lot of people whose support she would need by adopting that strategy (even more than she already has), thus weakening, not strengthening, her present position.
What if, however, she could create a situation now which would ensure that Obama would have to choose her as his running mate. If she could plant enough fears of a party schism in the minds of the remaining super delegates such that they would precondition their support of him on his taking her as his VP. Because he would need her, instead of merely wanting her, she would be in a strong bargaining position. She could use this position to insist on concessions from him. The more dire the prospects, the more strongly the supers would insist and thus the more drastic the concessions she could extract - up to and including the concession that he agree only to run for the one term and then cede the way to her in 2012 and promise to campaign on her behalf. This is the end-game which explains the paradoxical mix of full-throttle campaigning for the top of the ticket and overtures for the bottom position.
Why do I write this? Well, for what else does the internet exist except to document the random musings of every nitwit's idle mind and (if lucky) engage feedback on the same. So, what do you think? Does this theory seem a plausible hypothesis to account for the observed data which we have at hand? If you do find it plausible, does it fill you with admiration, or foreboding, or any other particular response? I am interested to read what others think.