To simply answer your question: No.
Even if it was, it seems inefficient to build multiple CSS files, etc. There are better methods than relying on resolution.
A longer-winded answer:
When 960 becomes "oh, that's so 2010..." how many of your sites will look dated? At the same time, not everyone that browses the internet has a 30" Cinema display either, or a dual monitor setup. I try to design to best accommodate MY traffic.
Although it may be nice to detect browser window widths, and/or screen widths (monitor resolution), I think the majority opinion is this: Know your intended audience and design/build for it.
Building a 960 grid and a CSS, then building a 1024 grid and a CSS = Inefficiency, and not very "future proof".
If you're watching your site traffic and see that 90% of your visitors are using 1 or 2 (or 3) resolutions, build a fluid layout that works well for that audience.
Fluid layouts are probably the best universal solution to the ever-expanding array of devices, resolutions, viewport sizes, screen definitions (low, medium, high) on the market now -- let alone 18 months from now.
Checkout @media queries to add to a fluid layout/design. Modify one CSS file (not 3). http://www.w3.org/TR/css3-mediaqueries/
@media screen and (max-width:960px) {
h1, h2 { color:#990000; font-size:1.4em; }
}
@media screen and (max-width:1280px) {
h1, h2 { color:#336699; font-size:1.8em; }
}
Add min- and max- widths
to your CSS (or a similar logic) can also help satisfy a wider range of resolutions/browser sizes, as well as give your design a longer shelf life. And doesn't rely on a document.window.width() function.
Get the most bang for your buck. Fluid designs, @media queries, javascript to help bridge some gaps. You'll end up with less code, a more "future proof" design, and a larger percentage of satisfied visitors.