A software developer in a healthcare company recently wrote the following description of their use of Clojure from their background with Java:
It's really easy to integrate into existing infrastructure in a Java shop. You can package libraries in it as jars that can be used from java code, you can build it with the same tools, such as ant and maven, and Eclipse support for it is quite good. Clojure applications can be deployed on app servers like Websphere or Tomcat, so in that regard it hasn't really required any changes to the way we already do things.
As a language it definitely allows for writing much shorter code, and it's easier to unit test, as it encourages writing small functions, the expressiveness of the language has been rather welcome, and the concurrency support in it makes life much easier for us. Overall we find it to be a very solid alternative to using Java for web applications.
The only negative so far has been the syntax, most people are not familiar with Lisp, and not everybody can pick it up easily. So, that certainly presents a problem for some people, but we've got a critical mass of developers interested in it to do a pilot project. So far the project has been going well and it is helping illustrate the benefits of using the language.
Even though we do not use Clojure, we have also noticed an increasing number of people referring to the Clojure language and that can only mean one thing!