In short, Google still has a supplemental index but they stopped labeling which pages are supplemental. Pages in the supplemental index generally don’t rank for much and the current thinking is that pages in the supplemental index don’t pass much link value. The lack of a label for these pages doesn’t necessarily change rankings for folks, but it does make it a little harder to figure out what’s going on with your pages. Boykin’s article (linked below) has a pretty good methodology for figuring out which of your pages are in supplemental hell. I enclosed another link to a news article at SE Round Table that provides a good summary of the situation and also links to some more good info.
Hope that helps. 