James Robertson is producing a series of screencasts providing a Smalltalk overview. I highly recommend taking a look if you are not familiar with Smalltalk. You've undoubtedly heard of Smalltalk and perhaps have seem some Smalltalk syntax, but if you've not seen the Smalltalk development environment in use, you might not understand how radically different the experience of Smalltalk programming is from developing in Visual Studio, Eclipse, or other file-centric systems. Even if you've programmed in a dynamic language such as Ruby and appreciated the "live" feel of REPL-style irb, this falls far short of Smalltalk, where your working context can persist from day-to-day and year-to-year.

Robertson works for Cincom and I believe is using the non-commercial version of his company's implementation for the screencasts. The Smalltalk environment, which has been evolving for more than 2 decades and has its own GUI conventions, can definitely be overwhelming at first, and the screencasts will help familiarize you with the territory.