I have installed javafx SDK a few days ago. I had a look at the javafx 2.0 sample applets and they were working fine.
Today I upgraded to the latest jre 1.6.0_26 and applets don't start anymore. There's a message saying:
"JavaFX 2.0 is required to view this content.
Make sure that you have a recent Java runtime installed, then get the JavaFX runtime from javafx.com and run the installer. Then restart the browser."

When I try to install the latest javafx runtime (built 30), the installer says:
"you already have this version of javafx installed"

I guess that the javascript that deploys the applet is making something wrong.