IBM VisualAge for Java was actually mostly VisualAge Smalltalk under the covers and provided a Java dev experience that for me has never been matched. When IBM dropped it for Eclipse, my productivity took a nosedive.
I don't care much about Smalltalk running on the JVM without the environment. I wish Redline success and hopefully they will create an environ as well.
http://www.pharo-project.org is a fantastic cleaned up derivative of squeak. Pharo 2.0 will come out of beta within a month. The 2.0 beta is good and Pharo v1.4 is also solid. The Cog VM http://www.mirandabanda.org/cog/, which is the newer VM that works with Squeak and Pharo is impressive. It doesn't have the tuning options and scale of JVM at the moment. I see no reason the Cog VM can't fairly quickly evolve to scaling on par with JVM for many use cases.
If the sugary syntax of ruby is a key motivator to use it over Smalltalk, that's cool. For me, I find the simplicity of the Smalltalk syntax combined with environment worth far more than the complexity of what Ruby has to do to provide all that sugar with little ability to reason about the code as a whole.
Scala provides language features that Smalltalk nor Ruby provide and those attributes may be more important for some.
In the language I work on we do use JVM classes, but our own methods tables are used to model the inheritance hierarchy, and methods are all static JVM methods under the hood so we can support all the meta programming that you'd expect in a Smalltalk inspired language.
Dunning-Kruger moment for you. Inheritance is in the VM for Smalltalk. So to avoid broken Java class side inheritance, they'll either have to modify the VM, which they can't do and maintain compatibility, or they have to have some support code.
My guess is that after a 10-15 year lull, Smalltalk is growing a bit. I'm very happy to see Pharo chugging along. I think that by 2014, Pharo 3.0 will be a hit. Pharo 2.0 is already very compelling for many use cases.
But seriously, things going for smalltalk: (a) a huge library of very extensive code, (b) a nice programming experience (though getting rid of images and adding files back would destroy that), and (c) it has a unique design that some prefer.
I think everyone should be exposed Smalltalk. It was my real intro to OO programming. It really is the pure OO language, where you can see objects unencumbered from all the non-object crud in more pragmatic OO languages.
Yeah… no. Smalltalk is much more than the Objective part of Objective-C, beyond even the development environment.
Also, I'm sure Objective C is the language still in mainstream use that most resembles Smalltalk (at least the non-C OO parts).
That's just... no. It has superficial syntactic similarity with Smalltalk's message-send syntax, nothing else of its syntax and (more importantly) pretty much none of its semantics.
For me, the Objective part of Objective-C is very close to Smalltalk, same dynamic messaging model, same perform(Selector):, same doesNotUnderstand/forwardInvocation handling, same ability to capture and replay messages, similar dynamic typing in the "object" part.
Recent developments are a bit of a mixed bag, Objective-C blocks are a welcome addition, though the syntax is cumbersome, ObjC finally got SmallIntegers.
In terms of "feel", the two can be very similar, though some of the libraries admittedly have a very different flavor and a lot of the recent activity in ObjC land has been pushing more in the direction of Java, which is a loss.
In the sense of objects being a means of connecting parts, ObjC actually seems closer to what I understand as the Smalltalk mission ("recurse on the idea of computer") than current Smalltalks, because it is so much more adept at talking to the rest of the world.
Differences, yes: the image, no "become:", memory management (very mixed bag on the ObjC side, but ...).
That said, ignoring the commercial Smalltalk implementations, I think that Pharo is the future of Smalltalk. The Cog virtual machine is reasonably efficient and the UI is in my opinion much improved over Squeak.
I am not sure how widely used the Seaside web application platform is used since the original authors went to work on other things at Twitter. At one point I thought that Seaside would give Smalltalk a lift in the same way that Rails did for Ruby.