Andrew Sullivan tries to differentiate Obama's "liberalism" from that of the past:

What makes Obama's liberalism different from both the technocratic meliorism of the Clintons and the 1970s big government liberalism that preceded it is that it is an inclusive, self-help kind of liberalism. It is participatory, not passive. It is not about government saving us; it is about us saving the government.

Bill Clinton famously said that the "era of big government is over"; I haven't heard Obama say that. Indeed, many of his signature policies (such as nationalized healthcare) are about expanding the role and powers of the federal government. So there's an expansionist aspect of government for Obama (as there has been for Bush, too). There also seems to be a compulsory aspect to "Obama's liberalism," as in Michelle Obama saying that her husband "will require you to work" and "will never allow you to go back to your lives as usual." It may be "participatory," but it also demands participation (or says it does).