There is some amount of questions about Jenkins/Hudson, and how to use them to achieve something. I have not paid attention to other CI systems, but I assume they have similar questions.
These are very much software development tools of course, but these questions are in essence, "Is there a plugin to do this? How should I configure it using a web form based UI".
Are these on topic now? Should they remain on topic?
Then there are also actual programming questions related to these, since they allow easy plugin development, and this is obviously on-topic. Though currently tags do not separate "how to use" and "how to develop for" Jenkins/Hudson, which IMO is a bit unfortunate.
I suppose this is very similar to, is "How to configure Visual Studio" question on topic, when "I have a problem with this Visual Studio plugin I'm developing" certainly is?
Note: I'm definitely not complaining about this, and there isn't any flood of these questions so it doesn't matter much one way or another. I suppose the other programming-related SE sites were started only after there started to be so many questions, that getting them to a dedicated site and out of SO was necessary?
Edit: Motivation for asking: I personally am interested in the development questions, not so much in the usage questions, but currently there is no way to tell these apart. There are actually 4 tags (jenkins, hudson, jenkins-plugins, hudson-plugins), which contain a mix of "how to use" and "how to program" questions.