We wrote an article for the Web Developer’s and Designer’s Journal that has been published in the November issue titled "Create a Photo Slide Show with Flex 2 and Picasa". It guides you on how to create a simple photo slide show in Flex 2. For this article, we decided not to use ColdFusion to appeal to a broader audience, so it just consumes the XML data produced by Picasa directly.
As usual, the source is available for download and we have a sample you can see live.
An update that includes transitions has been posted