On the Oracle website, a preliminary version of the JavaFX Scene Builder has become available for download:

The editor is designed for mouse editing of JavaFX forms. Consider what is in it:
Opportunities
As in most other formulators, you can use the mouse to drop components and set their properties. Some properties can be changed directly with the mouse (drag, resize, etc.), some can be set in the Properties and Layout tabs.
')
Additionally, for any component, you can set graphic effects such as reflections, shadows, blur, etc. You can also define CSS styles for components.
In the Events tab for each component, you can specify the reaction to events (click, keystroke).
A set of components includes both standard buttons, grids, combo boxes, etc., and graphic drawing primitives, as well as several types of graphics.
In the preview mode, you can even interact with the layout (for example, enter text into the RichEditor):

Final result
The edited layout is saved in an FXML file and can be used in JavaFX programs. The description of using FXML can be found at
http://habrahabr.ru/post/130057/ .
Layout can be changed in a regular text editor and Scene Builder recognizes all edits. For example, you can change the text property of the button:

Conclusion
The overall impression is rather positive than negative. In Scene Builder there are a number of shortcomings, for example, it is not yet possible to set the data for the grid or graphics directly in the editor.
Download Scene Builder on page
http://www.oracle.com/technetwork/java/javafx/overview/index.html , there you can also find JavaFX runtime.
Documentation:
-
Get Started with Scene Builder-
Scene Builder User GuideThe editor itself is written in JavaFX and requires JRE 6.29 or JRE 7 to work.