I'm not saying that it won't help you as a developer, but you probably won't get a job "in it."
Well, there have been postings to the extremeprogramming group on Yahoo, recommending learning SmallTalk (over C#!). If you do not *now* know SmallTalk, and you are not *now* part of the SmallTalk community, how would you teach yourself SmallTalk in such a way that it would help you get a job? Perhaps this objection applies to any language one doesn't already know. Still, one has only to type "Smalltalk" into CareerBuilder.com and see how few postings show up; there may indeed be SmallTalk jobs out there, but there are manifestly not that many.