I was going to put this in the comment section but then realized it was getting long and that I want people to see it.
After initially being pissed off about the things Bill was saying, I'm OK with his involvement with all the stuff Jon (and Maureen) talked about. It's certainly legitimate for him to be on the campaign trail; I never understood the whole tradition that former Presidents should stay on the sidelines after they are gone. I suspect it arose out of some tacit agreement between current Presidents who didn't want to weather the criticisms of former Presidents, and former Presidents who didn't want to stick their neck out on controversial issues.
However, I think it's useful to note that this is the first time Bill has been seriously involved politically since leaving the Presidency. During the Iraq war debate, despite "opposing the war from the beginning" all we got out of Bill was a milquetoast Op-Ed piece in the Guardian calling for people to support Tony Blair's UN resolution and multiple statements of support for the use of force resolution. During the Kerry candidacy, Bill made a speech at the Democratic convention, but then appeared above the fray, saying the day before the election that he liked George W. Bush and John Kerry (So, really, why vote? They'll both be fine, anyway).
Bill's explanation for all this has been his insistence on the aforementioned code of honor involving former Presidents, which he is now breaking with gusto. For people like me who once liked Bill, there's something depressing about the fact that he is now ditching the reason he didn't get involved before, when we really needed him, simply because there is something in it for him.
I think that gets to a larger point as well. When Bill Clinton came into office in 1992 there was a Democratic House and Democratic Senate, and after a generation without a strong Democratic president, there was a real opportunity for reform and renewal. When he left office he was extremely popular, but Republicans controlled both the House and Senate. His progressive legacy? NAFTA (although I support that one), welfare reform, the Don't Ask Don't Tell Policy, the Defense of Marriage Act, and the Iraq Liberation Act.
The vast majority of Bill's victories in the White House were personal ones. He survived his reelection battle, he kept himself from getting impeached, he got to take credit for the tech boom. For the progressive movement, though, these victories, while satisfying, were hollow. Triangulation sucked the life out of the Democratic Party. Until Dean came along, the Democrats' response to the Republican's insane power grab was to be like Republicans, only less so. And there would not have been a George W. Bush presidency had Bill not been so selfish and stupid during his second term as to get involved in yet another sex scandal and then (worse) lie about it.
I don't mind Hillary Clinton personally, but forgive me and the rest of us who don't support Hillary if we don't want to turn the party back over to Terry McAuliffe, Bill, Mark Penn and everyone else from the 90s who adopted the Nixonian philosophy that your principles are what you sacrifice to keep you in power when you get in trouble. Obama might not be the perfect candidate, or a saint, but he is, at least, saying the right things and promising to be different. Given that choice, I'll support him until he proves himself as dishonest as the Clintons did long ago.