I, too, would like to say that learning Smalltalk is a good exercise. I took it on after I learnt C and then I discovered Objective-C. Now that was fun :)

I've never found work with Smalltalk (or Obj-C for that matter) and I don't know whether there is much call for it. I work for one of those big "blue chip" companies that are always advertising on Jobserve, etc. They like big well know things from big manufacturers so there is a lot of call for Java, C++ and .NET. Perl, for my company at least, is extravagant - I don't think I'll ever see them approaching me for Smalltalk :)

However, getting back on-topic (loosely though it is :), I'd say go for it - it really helps with OO thinking.