in unix you can use owhat which does not always work heh, but there are other tricks in unix, you need to look on

http://metalink.oracle.com/metalink/...T&p_id=69118.1

or simply run Universal Installer which tells you what has been installed, or look oraInventory but for patches like replacing a .so your best bet is follow that paper or simply compare the .so file (which are usually small!)