In this new post to his blog Chris Hartjes looks at why "monkey patching is for closers" - how it should be avoided in favor of making the code itself more testable rather than "hack" with the patching.
The use of monkey-patching is extremely prevalent in the Ruby community and also to a certain extent in Python usage. I'm not going to go into length about their use of it except to say that it seems quite common and I think most developers are using it as a shortcut to counter what might be poor code architecture decisions.
He includes some example code, excerpted from a blogging system where runkit was originally use to test its functionally. He shows how some simple refactoring (adding input parameters, replacing a static method call, etc) makes it easier to unit test. Comments to the post include further refactoring ideas as well as a response from the original "offender" whose post sparked Chris' response.