I happened across this comment which I think gives a flavor of image based development.
'So while I can and do use the JVM for server-side computation, it’s a bit heavy weight for small and simple tasks. Common Lisp’s answer to this problem was an ingenious one. Instead of building programs that you run over and over, it offers an “environment” in which code is iteratively evaluated, so that you actually grow and nurture a burgeoning set of functionality within a long-running VM. I like this model when appropriate, and enjoy it, for example, in Emacs, which I can leave running for days on end while at the same time extending its functionality by writing new functions and customizing variables."