API and application developer or experts wanted

We are looking for an API developer. The project involves the development or enhancing an existing PHP based API and the development of sample applications for the API. The API should be able to work with mobile devices too (which is what APIs can also do). The API should allow for other to develop applications linked or as client to the API. We are open to suggestions on best language to use enhancement to the API. The ideal candidate should be available for regular updates and work closely with the project manager.