ok, I upvoted this simply because it had Smalltalk in the title. However, I have to chastise the author for not really saying much except he wants people to throw their vote into some support with zero detail on why IntelliJ makes any sense as a Smalltalk IDE. IDE, in the traditional Smalltalk sense, doesn't have the same meaning as it does for IntelliJ's other languages.
Why not write your own language plugin, and then let JetBrains take it over? That's what me and another group did for Clojure. The language plugin API for IntelliJ is very nice. It's not documented very well, but it's easy to get help from the IntelliJ language plugin community.