I don't expect that Ruby will be the last language I ever work with. In fact, I expect I'll probably be doing something new in the near future. The question is what language should I work with next? Should I go for a classic like Lisp or Smalltalk? Should I give Scala or Erlang a shot and ride the concurrency wave?
The problem is, I'm asking the wrong question. Rarely when discussing languages do the languages themselves dominate the conversation. I can't remember ever being in a conversation where someone won a language debate with things like closures, metaprogramming or static typing. Instead, the primary focus of language debates are usually around frameworks, performance, IDE support, developer availability, what OS does it run on, and any number of other factors that are only related to the language.
The question extends even beyond factors related to the language.
At Google I’ll work with C++ rather than (for example) Ruby but I do get to be part of changing the world. -- Jon TirsenJon gave up a job using his language of choice to work with another language he likes far less, but for a cause he's very interested in. I have another friend who recently starting working with an investment company because he was interested in the domain.
Two years ago I started looking at Ruby because several of my colleagues were giving it a look. I preferred Rake to NAnt, and starting using it on my .net projects. Before long, someone asked me to be part of a Ruby project, because of my limited exposure to Rake.
I got introduced to Ruby by coworkers who were interested. I got involved with Ruby because I prefer build files that do not require XML programming. I stuck with Ruby because we had a steady stream of Ruby projects that needed experienced developers, I got plenty of blog content, I liked the composition of the Ruby teams I got to work with, and I liked working with clients who are comfortable with early adoption.
Notice, none of the reasons I use Ruby have anything to do with the Ruby language itself.
I'm interested in doing something new because I feel like I've been doing the same thing for about a year now. I'm also interested in traveling to other ThoughtWorks offices and getting some fresh ideas for innovation.
Again, none of my desires have anything to do with language.
I'm not giving you the tired "no silver bullet" or the hand waving "the right tool for the right job". I'm asserting that people use those phrases to justify their language choice, but you'd be better off asking what the real motivations for choosing a language are. What other factors does the language introduce that make it their choice.
It's also helpful to have this understanding when considering criticizing someone's language choice. My friends aren't using Java because they like Java, they are using it because they like IntelliJ, high performance on a few boxes, simple deployment, Hibernate, String Template, Spring, and a hundred other factors. Therefore, criticizing Java as a language doesn't really do anyone any good. Even if I convinced them that Lisp is a better language than Java, I still wouldn't have convinced them to use Lisp on their next project.