I just attended Scott's presentation on filtering and sorting in Flex 2 and it was very well done. I had done all of this before myself, but honestly most of my work was copying from the docs (or from Scott himself!), and it was darn nice to get a 'real' lesson behind what was actually going on. If you get a chance to see this presentation (I think he is giving it at the next Flex conference), definitely make the time.