My dream for the Javeleon project (http://javeleon.org/) is that it will enable me to start up an application during development... and then never need to close it down again. I don't really care so much about application state: if it means that I can reload my modules into the running application, then whether the state is maintained is of secondary concern.
That perspective isn't, strictly speaking, the primary focus of Javeleon. Still, things have come a long way and in the YouTube movie below, you see me (silently) creating a new application on the NetBeans Platform, via Javeleon. The point of the movie is that I make a pretty cool, albeit small, application, without ever needing to restart it during development. Hope it inspires more people to try out this really amazing plugin!
Note: At JavaOne, on Wednesday 3 October, from 15:00 to 16:00, you can attend a session on Javeleon, presented by Allan Gregersen, Rene Jahn, and myself: Dynamic Class Reloading in the Wild with Javeleon