The idea of building a cmf came to me 2 years ago, at the time i wasn't into php frameworks, i intended to build it from scratch and i came very close to a release candidate a year ago but my pet project had to be put on hold. I started work at Greek Ministry of Education and i was involved on a lot of web projects and to speed up the procedure i choose Zend Framework as the industry standard choice. That's when i fall in love with php frameworks. Zend 1.11.x was easy to work with, it didn't bound the programmer to follow a strict path and had (probably still has) a huge variety of libraries to accommodate any programmers need. Another big factor on choosing Zend was the excellent documentation and on-line sources.
Six weeks ago when i decided to restart my pet project i had to choose between continuing with my php framework or go Zend. Unfortunately my php framework had to die young because i wanted to have something ready for production this year. Zend framework 2.0 was well under the way but at the time only beta versions had surfaced. I have to admit that after peaking at the source code of ZF2 i wasn't impressed but i won't comment on it until i have the time to check the stable version that was released last week.
After that i was on a php framework hunt and limited the options pool to Symphony2, Kohana and Lithium. I quickly eliminated Symphony because it looked like it has a very steep learning curve. Kohana, although i promise to keep in touch, is lacking in cutting edge PHP features. After quick tests i was impressed with Lithium. It's relatively small and fast, it doesn't impose stupid restrictions to the programmers and has a better than good in-house Data Model solution. Of course it has some grey areas but because it's so flexible you can bypass any problem or bug easily.
But i have to admit the number one reason for my choice was the news about Lithium getting sponsored by Engine Yards. Honestly Lithium development has slowed down a lot this year and until the news from Engine Yards i wasn't sure if Lithium was dead or alive. Documentation is sketchy at best, online sources are limited and git support is, well hrm... If you are new to php go with a framework with good documentation and community like CakePHP, otherwise be prepared for a lot of code reading or stay tuned, lithium tutorials are on the way...