The folks over at Fortrabbit.com have officially announced the opening of their cloud-based, PHP-focused hosting platform:

We do managed hosting for over 5 years – a business where reliability is one of the core values. And Platform as a Service is just a label for a modern approach of scalable hassle-free hosting solutions. This PaaS market is very young and still a changing category in the wide field of cloud hosting. Listening to customers and their needs will influence the way current services work.

They offer a "Bootstrap" service if you'd like to try it out. It supports PHP 5.4, APC, MySQL, Git integration, Composer support, SSH/SFTP access and DNS management. You can also add on memcache and SSL support if desired.