I noticed StackOverflow appears to be targeting screen resolution widths of 1024px or more. I also checked Amazon, NBC, MSN, & AOL which target more lay users, and they all appear to be targeting the same width.
Is 1024px the current recommended width for web apps targeting the largest cross-section of users who use default monitor resolution/browser size?
Unsophisticated? I think that's a bit of a rude way to describe the unwashed masses. I suppose every one and their dog has a 1024px width monitor now thanks to the likes of dell and others...
Use liquid layout. Then you can easily accommodate everyone from ~800 to ~1600 width, and with a bit more work and care even lower-resolution devices too. This also gives users @1024 some leeway to zoom the page if they find the text too small.
Remember there'll be things like netbooks which don't have the big screens we expect today. You can get away with a horizontal scrollbar, but if you have to scroll the page just to get the main body of text in, you're lost.
Before sounding so condescending, you may want to read up on the modern user base. Netbooks. PDAs. Smartphones. Smartbooks (you do know what those are, being very sophisticated, right?). Programmers who have their screen in portrait orientaton. People who stack their windows side by side. Kiosks.
UPDATE As per conversation with John, I edited the question to change the tenor a bit to reflect his original intent. However, the original paragraph that I wrote is still true- I haven't seen the latest statistics but the days of "90% of users have AxB resultion/window size on their browser" are probably forever gone, what with wide screen laptops and mobile devices. Makes life more exciting for UI designers :)
Having said that, to develop a really usable web site, you need to couple flowing layout with, ideally, ability to use portlets and portal framework (think My Yahoo), so people can choose the page layout most comfortable for them.
The maximum I would consider targeting as my "base" is 1280x1024, but I would be much more likely to go 1024x768.
That said, in my current projects I try to do a liquid layout with a min-width of 800 to accomidate netbooks and usually a max-width of around 1000px (970 usually). Of course, I also have the luxury of designing for myself, so I have the privilege of telling IE6 users that they should upgrade, which makes the liquid layouts much easier to design.