I think that when transparencies are used correctly, they make a very nice effect. It looks pleasing to the user, gives a much greater sense of depth and a feeling of being in a 3D space. There are definitely times when transparencies can be overkill, but all in all, I think they will have a significant place in Rich Internet Applications. Tim Sneath talks here about adding the Aero Glass effect to Vista forms. It's a very good read, and he included a sample screenshot. Well Kevin Hoyt at Adobe sent me a Flex 2 example which mimics Tim's. To be clear, it's not the same effect as the Aero Glass that will ship with high end versions of Vista, that is a bit more advanced, but it's a good implementation of transparencies. I think looking at them side by side shows that we'll be able to do some very cool things with the technologies that are coming.