Hi Turgay,
The PHP library uses web services to access the Alfresco repository and allows PHP programmers to access an Alfresco repository.
In version 1.1.2 there are a number of Alfresco web service which provide the core services (repository, content, authoring …). I am currently working on the next next set of web services for the 1.2 release (actions, rules, access control, dictionary, admin, …).
It is our vision that eventually all of the Alfresco services will be available via a web service interface and thus to languages like PHP.
As well as the PHP client web service stubs for the Alfresco web services, the PHP library also provides a number of 'wrapping' objects that try to abstract some the difficulties of working with a web service stub, thus providing a more intuitive PHP API.
The PHP library is still work in progress, but it does include a working UI example that can browse the repository in a similar way to the main web client.
Hope this helps,
Roy