Calling the protesters liberal misses the point. They are too diverse of a group to be reliably called a liberal movement. The protest is designed to be a diverse, distributed, muddled mess. It is neither liberal nor conservative- there are people who would identify as both groups participating.
The big point of the protesters is that the wall street banks are causing a problem in society. Beyond that they are more or less deliberately shunning identification as a liberal or conservative movement.
It is much more similar to the protests in egypt, tunisia, etc. that happened this spring than to "liberal" protests such as the anti-war movement in the 60s and 70s. That is, it's a diverse cross-section of society angered by wall street greed- and only that. Beyond that one basic premise, very little will probably unite the protesters as far as ideology, demographics, or messages goes.
Read John Robb on "open source protests" for more details on this view of things.