[drather19]

We use Smalltalk for a good portion of our distributed control system on our semiconductor manufacturing equipment (at least the non-RT critical portions). It's actually sort of awesome to be able to test/rework/enhance the software on the fly as we discover things we'd like to change in the clean room without having to go through traditional implement/build/deploy cycles. There's certainly other caveats about working in the environment we have, but those we can chat about offline :).

From what I've read and played with (briefly), JRebel gives you a bit of this experience on the Java side as well, though I've never used it extensively enough to know if it delivers a comparable experience.

It's not that far removed from what many web application developers take for granted in terms of ability to make/test/refine changes on a live system with ease, but it does bring more of this experience to other functional domains.