We've been doing a tech preview release for a select group of Servoy developers for a while now, and soon the Servoy 4.0 public beta will be available. We get many questions about what developers need to do to get ready for 4.0, so I've got a blog post to help you get started.
http://www.servoyguy.com/blog/getting_ready_for_the_servoy_40_release