Bruce Eckel has an interesting post on hybridizing Java with Flash. He notices the trend in the Java world to replace Java-based GUI frameworks (AWT, Swing, etc.) for Java apps by Flash.
Incidently, I came across one such app yesterday evening when I installed PowerSnap. The UI indeed was somewhat snappy. This application claims it can keep your locally stored photographs in sync with those posted on Flickr.
Of course, the major benefit of using Flash over UI technologies as WPF is reach. WPF only runs on a subset of the Windows platforms. PowerSnap is working on a Mac version which should be relatively easy because Java and Flash are available on the Mac.
Maybe in future versions it can be used for the GUI layer of a standalone cross-platform .NET application. Microsoft is quietly working on versions of the CLR that will run on other platforms so that WPF/E can be "scripted" using C#. The work done by the .NET Compact Framework team already proves that this is possible. This CLR runs on devices like SmartPhones, PDAs and the Xbox 360.