What do you think is a good IDE for learning SmallTalk? I'll only be using it as a hobby, so it has to be free.
You should also consider Pharo. Pharo is a fork of Squeak. Their goals are:
a clean and lean open-source Smalltalk platform, derived from Squeak
the obvious choice for professional Smalltalk development
an emerging platform to help people invent the future
Whether it is Squeak or Pharo, there is a large, active and supportive community.