This past week has seen an explosion of new... um... let call it web 3.0 toolkits for lack of a better term. AJAX replacements basically. In addition to Adobe and Microsoft's early contenders (Apollo and Silverlight respectively), Sun announced JavaFX as a third contender. Sun's announcement comes on the heels of their initial follow through to open source the Java VM with the SDK coming soon.
My understanding of these frameworks is very limited, other than Apollo is based on Flash, Silverlight on C# and JavaFX on... well... Java.
As Mark Piligrim points out, the proprietary nature of these frameworks runs counter to what makes the current web technologies successful. JavaFX had not been announced yet, so I wonder what he thinks of it given Sun's willingness to release Java under an open source license. Of the three, it's probably more the underdog that the tech community will try to rally around.