From 1.2.1 release on wards, we did not release the .deb and .rpm packages for WSF/PHP. This was due to number of reasons.When the number of release packages were big, the testing process involved becomes lengthy. Also due the different versions of operating systems these packages have to be built for each version. Since the limited about of resources and time availability, we decided to release only the src packages for linux , and binary and src packages for Windows. Also we released a pecl package for Linux as well. In case you are using the PECL package, you will also need to download and install the dependency library WSF/C. Therefore, it is always easier to download and installed the src package, since it contains all the decencies as well. How ever we did not remove the installation instructions for deb and rpm since it might be useful if one is using and older release which contained deb and rpm packages or if one wished to build them manually.
In case you want to build the binary packages for linux yourself, you can find the installation instructions here.