Clive Crook's gloss is right-on:
Take this budget at face value, and when Mr Obama talks about “a new era of responsibility” he does not mean: “We are all in this together.” He means: “The rich are responsible for this mess and it is payback time.” Leftist Democrats are thrilled, and rightly so. The budget has three themes: healthcare reform, public investment and unflinching redistribution. This is indeed a new social contract: we get, they pay.
This is, in fact, one of the reasons I am increasingly optimistic about liberaltarianism. I predict Obama's unabashed embrace of throwback, dirigiste, soak-the-rich “liberalism” will not prove popular with generally pro-market, well-to-do voters who crossed over for the first time to pull the lever for a Democratic president. Yet the not-very-religious remain repelled by social conservatism all the same. As I've said, it doesn't matter to me whether the Republicans become more liberal on “values” issues or whether Democrats adopt more sensibly market-oriented social and economic policy. Either way, by signaling the desire of contemporary Democrats to move even further left than is feasible in the U.S., Obama draws attention to the unoccupied space in American politics.