I wonder if you are talking about what we now call liberalism (this is what the first two answers think) or if you are talking about what we now call classical liberalism.
I do not really think that classical liberalism exists any more. Classical liberalism believed in a laissez faire government with regard to economic issues. It believes in a very limited form of government that has a very limited role in people's lives.
I think that perhaps this can no longer exist today. Our society has become so complicated that it seems that government has to take a larger role than classical liberalism could have imagined. I think that you see this in the fact that only there are really no mainstream political parties in the West that advocate government as limited as that of the classical liberals.
If the question seeks to examine the viability of political liberalism, I would suggest that it can exist. Having said that, I think it should be noted that it is challenged by many elements as it strives to exist. The idea of being a "liberal" used to be seen as a bad thing in American Politics. Some suggest that when then candidate George H.W. Bush branded fellow candidate Michael Dukakis as a "Card carrying member of the ACLU," it helped to label him as a liberal, something that he never quite escaped through the campaign. Since the time of Regan, liberalism had been seen as quite a bad thing in American politics, something from which few could escape. The American political landscape of the 1990s helped to move the political balance more towards the middle of the spectrum, with liberalism still being on the outside looking in. The new era of politics, one that has seen the attacks of 9/11 as well as the current economic crisis, has softened its rebuke on liberalism to a certain extent. The passage of health care initiatives as well as the passing of Senator Kennedy, affectionately called "the liberal lion," and the reexamination of values from the George W. Bush era have all helped to allow liberalism to be something that can be, once again, seriously evaluated as a political option. However, it is one where individuals still throw "red meat" slogans such as "too much government is not needed" or "socialist" or "like Russia." In this light, liberalism ideology can still exist today, but has to be politically savvy enough to be mindful of the criticisms that still exist against it and present itself as a viable political option for those who are in need.
This is a good question, but also vague. Liberalism as an ideology can mean many things, but a few themes usually are tied to liberalism. Liberal are usual more open to other people's view points. Liberals are more relativistic and pluralistic in their views. Liberals also have a pretty strong discourse about social justice and the importance of helping the poor. If we define liberalism in these ways, then sure it exists today. I would say that it is the dominant point of view in the cities of America. The positive aspect of this way of thinking is that it tries to account for other people's opinions and points of view. Also it tries to be inclusive. The weakness is that it has a hard time saying one point of view is better than another.