My first encounter is Visage Smalltalk as part of the study to replace the VSE mainframe :-). But even the IBM SE is not that confident. Hence, we are off. (And strangely one of the issue is the source is too available, that the environment is too open to manipulate ... sorry just too used to COBOL and Java like fixed program than this dynamic things :-)).
But for the main history, just read about how Steve Jobs during my search of HOPL 4 about Next history that he missed the two key elements of the Lab (Ethernet and Smalltalk). He fixed both on the Next computer and in fact the prototyping and performance of Interface Builder and the underlying Objective C is so much practical than Smalltalk is too complicated.