I am of the opinion that Java Fx has a big role to play in web 3.0... According to Sun's Boss Eric
".........But if I were to guess what Web 3.0 is, I would tell you that it's a different way of building applications... My prediction would be that Web 3.0 will ultimately be seen as applications which are pieced together. There are a number of characteristics: the applications are relatively small, the data is in the cloud, the applications can run on any device, PC or mobile phone, the applications are very fast and they're very customizable. Furthermore, the applications are distributed virally: literally by social networks, by email. You won't go to the store and purchase them... That's a very different application model than we've ever seen in computing."
My emphasis is on mobile phone. The java fx mobile framework i believe will leverage so much on the already existing j2me JSRs(especially the mobile game APIs) to provide rich, affordable contents to mobile phones. Although we have Flash&Flex, Microsoft&Silverlight and Android, I am of the opinion that JavaMe has a stronger foothold on the mobile world than any of these technologies and if my presumption is right, javafx mobile will sit pretty atop J2ME to provide contents that are rich and affordable....
Although JavaFx for CLDC is yet to be fully functional, I definitely believe Sun is having some kittens in their cupboard which I am of the opinion they will let us see at the JavaOne conference. I also see a future of JavaFx for other portable devices running CDC and if all went well, JavaFx might as well be called Applet 2.0 for the Web End.