I'm an enthusiastic Smalltalker since joining Objectory AB in 1994, and discovering that I could become a productive developer using Smalltalk after no previous experience in the language, environment or target application in about 2 days; a serious hacker after about 2 weeks; and really dangerous after six months.
I learned Smalltalk from such excellent mentors as Sten-Erik Bergner, Ingemar Allqvist and Gunnar Blomberg, and was able to get Kent Beck to come over to Sweden in 1995 to give us a talk on his then-work-in-progress on Smalltalk patterns.
What I see as the Smalltalk development style carries through in all software development I do, and I think the mindset that Smalltalk and the Smalltalk community forsters (which involves such things as highly iterative development, focus on developing appropriate abstractions to express problems and solutions, extensive shifting of programming solutions into generic code solutions coupled with data supplying the instantiation for a particular solution) is very powerful.
I have worked on a number of software development tools: Sysware Matrix, Objectory SE and BE, Rational Rose, Rational XDE, IBM Rational Websphere.
I am currently working on a software development platform and scalable server for mobile devices at Sproqit.
Smalltalk is my favorite language and development environment (although Apple's Dylan(footnote) environment gave it a run for the money before it was cancelled), but after using ParcPlace's ObjectWorks and then VisualWorks professionally, I haven't had much chance to use it, except for the occasional hobby project in Squeak.
I'm currently hobbying around using Python, Objective-C, C#, VisualBasic, and sometimes Squeak.
Someday I hope to bring the Smalltalk software development "mindset" as I see it to a wider audience. Whether it will involve actual use of Smalltalk or not remains to be seen.
I think many of the Smalltalk valuables (dynamism, great classes, great tools, block closures) exist or can be replicated in other environments, but I do think Smalltalk environments have the best combination of such valuables.
The top of my wishlist for Smalltalk are:
1) Tools for dealing with components in various ways.
It's way too painful to incorporate new versions of Squeak. I like the way Smalltalk file-outs can inject changes anywhere in the class hierarchy, but the current tools and practices aren't quite good enough. SqueakMap shows promise, but often doesn't work.
I like the way NeXT/Apple allows deployed code to deploy and reference specific versions of code it depends on.
2) Better server competitiveness. I tried using Squeak on a server with no X-Windows installed. I never got it to work properly. Don't get me wrong; I'm not whining or begging anyone to do. It's just a pity that it seems it's easier to put together a solid server solution at this time using Python, PERL or Ruby than it is with Smalltalk. It seems like a sadly (so far) lost opportunity. This may be more of a perception problem than actual technical merit. I don't know.