The history section of the wikipedia entry on rails says: "Hansson first released Rails as open source in July 2004, but did not share commit rights to the project until February 2005."[1]
The very second sentence of the wikipedia article on CakePHP is: " It follows the model–view–controller (MVC) approach and is written in PHP, modeled after the concepts of Ruby on Rails, and distributed under the MIT License."[2]
Then, in the fourth paragraph: "One of the project's inspirations was Ruby on Rails, using many of its concepts. "