[eluser]OverZealous[/eluser]
The short answer won't make you happy: I'm the only developer. For the foreseeable future, this won't change, although I accept suggestions and patches.
I do maintain it in an SVN repository, but it is privately hosted. I'm thinking about migrating to mercurial - but that benefit is for me, not necessarily to open it up more. I'm kind of the DMZ dictator, and I don't want turn this into a full-time job just verifying check-ins, etc.
However, the good news is that everything that is important for developing DMZ is included in the download. It is ridiculously open-licensed, so anyone can take it copy it, modify it, resell it, or whatever. The only thing is that I retain copyright over the phrase "OverZealous", the DMZ logo, and there are some less-openly licensed graphics in the sample application.
I use DMZ exclusively in my own application (ZestyJobs), and will maintain it as long as I am able to. The only thing I've cut back on is supporting the HTMLForm extension, because it was just too much code for me to maintain alongside DMZ.
As far as upgrades go: The only things I plan on changing between 1.X and the eventual 2.X are not so dramatic. I'm mostly planning on clearing out legacy code, possibly migrating some of the lesser-used functions to extensions, so they don't take up resources (and lines of code) if they aren't needed, and those sorts of changes. I also may re-format the entire code base, because I personally don't like having the braces on their own line (I'm a Java guy originally). :-P
There will be an upgrade path, and it should be fairly painless. The majority of upgrade hurdles so far have affected developers who needed, for one reason or another, to access non-API methods, or manipulate undocumented internal properties.
One thing that might change that is how much work is needed to support CodeIgniter 2.0. If CI 2.0 requires a significant rewrite, I may use DMZ 2.0 as a clean break. However, as long as I've switched to Hg by then, I should be able to support both the 1.x and 2.x lines simultaneously for a while.
Finally, I most likely won't be supporting CodeIgniter 2.0 until it is released. It just isn't high on my priority list.
