Fair enough. I guess we do have a system for making rapid changes in place, and I'm just used to be able to do that sort of thing regardless of the language.
We are consultants here in Bangalore and we have routinely done this on a Python/Django social networking web app and a Ruby on Rails web app. code-test-svn commit - svn export , pretty much.
With a lot of java experience, I can say that it is more elaborate and laborious in Java than python or ruby. The erlang movie (http://video.google.com/videoplay?docid=-5830318882717959520) shows off the same, for erlang.
It's also true that I assume these things are just like that partly because I founded a company that handles build and deployment... http://www.electric-cloud.com