This might seem like more of a graphic design question than a programming question, but I think it has much more technical/programming merit than actual graphic design.
The concept of "responsive" web design revolves around using media queries in CSS3 to detect the size of the viewing device and adjust the CSS rules accordingly - essentially, dynamic CSS. This fills the void on a lot of deployment cases - mobile, in particular.
I think use of media queries is surfacing slowly (I've found that many people don't really know about it), but I'm wondering if there is a reason for slow adoption. Is it impractical for web applications? Is there something I'm missing that might be a fundamental pitfall?