Wow, Smalltalk is cool. I've been examining both its current uses and its history. Mainly, the two things that stand out to me are that SmallTalk is a much more influential and powerful language/environment than I had initially given it credit for, and also that Objective-C borrows a lot from the language as well. As a note on that second observation, I'd say that one could almost put Obj-C in the SmallTalk family. Most of my exploration has been through the Squeak version of SmallTalk. I've looked at Dolphin briefly, but it is Windows-only and appears to be nearing the end of its life according to the developers.
Versions to examine: