NeutrinoCMS is a publishing system for developers.
In beta release, a lot of code was fixed and rewritten, with simplicity as the primary guiding thought.
Before installing, take a look at the ~/docs/INSTALL for some basic instructions. If you're updating from a previous version, read the update instructions in ~/docs/UPDATE.
You will need at least CakePHP 1.2 RC2 to run NeutrinoCMS, and I assume it will work just fine with the nightly builds too (not tested though).
Test it, play with it, try to break it, and send me your comments, suggestions and bug reports to <neutrinocms[at]gmail.com>
Your feedback will be greatly appreciated!