Question - How far can CSS be taken beyond the web page--that is, have generalized or non-web specific features for such things as page formatting or type setting?
Answer -
Yes, it's possible to take CSS further in several directions. W3C just published a new Working Draft which describes features for printing, e.g., footnotes, cross-references, and even generated indexes.
Another great opportunity for CSS is Web Applications. Just like documents, applications need to be styled and CSS is an intrinsic component of AJAX. The "AJAX" name sounds great.