There are always quite some blog posts on installing SOA Suite on several platforms. Recently I discovered that Oracle publishes a Quick Start Guide on the SOA Suite (PDF!) that mainly deals with the installation process (and de-installation should you need it).
This guide is aimed at installations for developers and not for production machines. Unfortunately the installation of OSB is out of scope. I expect it to be upgraded to PS4 (126.96.36.199) soon. I could find any missing instructions while installing PS4 on a Windows7 VirtualBox.
This document looks very similar to the installation chapter in Getting Started with Oracle SOA Suite 11g R1.
The update for SOA Suite PS4 (188.8.131.52) including Oracle Service Bus is now available.