About a year ago a friend and I tried to build a social network for some niche and forums were one of the functions. It is pure LAMP code, written in Yii framework. Since the project failed, I'm trying to get all the rights to publish the code under GPL. My plan is to also run a small social site for programmers as a proof of concept and having a real-world website where the code works. Of course, there are some things specific to our project which I need to remove/refactor first, but it is not too much work.
If anyone is interested in beta-testing when I release the first public version on github, please drop me an e-mail and I'll let you know when it's ready (my e-mail is in my profile).
A few years ago I tried different PHP frameworks. CakePHP seemed too strict with database schema, Zend seemed too complicated. I built large applications with CodeIgniter, it's ok but lacks features. Kohana docs and support did not promise much. Laravel did not exists back then. So I tried Yii (it was version 1.0.something) and it was great. Quick prototyping, powerful, but simple enough and good support on the forum. I built a lot of apps with Yii and this experience influenced the choice because I knew I wouldn't spend time learning the framework, but building the product instead.
Especially, since I built my last 3 projects using Node.js, it seemed that learning another PHP framework like Laravel would not benefit me too much. Now, you might ask why did I not go down the node.js route. It's because I wanted to build LAMP based code which I could eventually open source if the project fails. I plan for it to become a standard PHP package for social-network type of sites. You know, just like you have Wordpress for blogging, you could use my engine for small social networks, or just MVPs.
If anyone is interested in beta-testing when I release the first public version on github, please drop me an e-mail and I'll let you know when it's ready (my e-mail is in my profile).