Can a new custom component (Class) be added to the Matisse Palette?
Can the order of the existing components in the palette be changed?
Is it possible to add a divider to the list of componenets, or add a new 'folder' containing the custom components?

1) Custom components: This feature is comming soon, we had technical limitations keeping us from adding it, hopefully it will be added by 5.0 GA, but not sure yet.
2) Order: I don't think so.
3) A divider can be added to your form using the "H" looking control for JSeparator. If you mean a divider or folder in the component tree, no. The closest thing you will get to a "Folder" is to create a new JPanel and place your components in it. But keep in mind, this is not an organizational construct, this will also effect how your form is actually laid out.

When is version 5.0 GA Scheduled for release?

August 6th for the time being.