By traditional "Smalltalk dev environment", I assume you mean an image. If that isn't correct, then my entire response isn't going to be off base.
We are currently aiming for file based support with optional image support coming later down the road. Even in a file based system, we will have resumable exceptions and reloadable classes with the image.
The website is very much a work in progress, we do have a page up that attempts to answer some: 'Why the JVM' questions.. FAQ for things like 'Will you support an image' is still coming.
http://www.redline.st/discover/why-the-jvm.html