PAF4 is still available. At http://www.familysearch.org/http://www.familysearch.org/ click on Download PAF, fill in your name and email address, and click the Download button beside English (v4.0.4) (5.8 MB)
On the other hand I prefer PAF5, which is almost identical but supports gedcom standard 5.5, and has unlimited Note size, and a few other goodies. PAF5 will read your PAF4 files and convert them to PAF5 format. So you lose nothing by switching to PAF5 except the ability to convert PAF2 files.