Many believe that JavaFX is too little too late for Sun to become a player in the rich client space, but I think that if Java 6 U10 is successful that Sun will be making it's critics eat their words.
I recently tried to install a tool for Dojo that was created using the Adobe Air framework, at the time of installation, I was informed that "Air is not available for your platform".
You see, I'm using Linux (OpenSuse 11), and in fact most of the workstations in our office are running Linux now. The problem with Air is that it relies on a newer version of the Flash player, and that particular version isn't ready for Linux yet. This is always an issue when you are relying on something that's not truly open, such as Flash.
Sun has shown commitment to "openness" by developing FX and Java in the open source community, and it's stewardship of Java has always treated the platforms supported by Java as first class citizens, this in the long term, will be JavaFX's greatest strength.
Now before people discount Linux as a fringe platform, with Vista being a flop, there's increasing momentum towards Linux as a viable player in the corporate & consumer desktop, in fact the Asus EEPC was one of the best selling computers in 2007, and it's Linux based! Even more Linux based devices are coming from vendors such as Dell, HP, Asus, MSI and others, and JavaFX and Java will run on all of them.
I do agree that FX is getting a little late, and the time for Sun to move is now, if they don't get it out of the door soon, even the strength of the Java platform won't be enough to ensure JavaFX adoption en mass,