Just worked on a project that used CakePHP [http://www.cakephp.org/] as it's framework. It was very straight forward in picking up and working with, as it follows the normal MVC methodology which I like a lot.
There were a few things that needed to be named correctly to make the most of the framework, which was interesting, but no big deal. As they do a good job of providing some decent documentation on the system and had a decent tutorial.
The version I used was the current stable release [Stable: 188.8.131.5205], but it appears that the latest release is fairly standard with some new features/improvements. The main thing that I noticed in the time I worked with it between the versions was the Form helpers being separated from HTML helper.
The project was pretty straight forward in just being a dynamic website with the usual CMS functionality.
I definitely want to try the framework out on a more demanding scenario and hopefully that will be happening soon.