I've been seeing a lot of Liquid Page Layouts popping up lately. I have to say, I just don't get it. Maybe people just aren't doing it right, but it rarely makes my viewing experience any better. Point of fact, most of the time, I find a liquid page harder to read. Think about newspapers for a second. Do you ever see a newspaper have full-page (horizontal) columns? Never, not once. There's a reason for that: it's hard to handle the line breaks when you have to move your head/eyes back and forth so much. If you disagree with me, you disagree, but I think that's a widely accepted fact.
So what is it that makes people think this is so right for the web? Yeah, we all have different sized monitors, but so what? I have a luxurious 1280 x 1024 monitor, but that doesn't mean I want to read across 1280 pixels of text. Maybe it's because we are programmers, not designers. Maybe we just don't understand user interfaces? I don't know. All I can say is that from PERSONAL EXPERIENCE, viewing a 800 x 600 site on a 1280 x 1024 monitor is MUCH nicer than viewing a 1280 x 1024 site on a 1280 x 1024 monitor.
Of course, there are always exceptions to this. Some sites do this very well. Most sites do not.