There are no hardware requirements for the SAML v2 Plug-in for Federation Services. There are, though, hardware and software requirements for the underlying Access Manager and Federation Manager servers into which the SAML v2 Plug-in for Federation Services must be installed. See the documentation set for the appropriate product to view the respective hardware and software requirements.
Sun Java Enterprise System 2005Q4 Release Notes contains hardware and software requirements for Sun Java System Access Manager 7 2005Q4.
Sun Java System Federation Manager 7.0 Release Notes contains hardware and software requirements for Sun Java System Federation Manager 7 2005Q4.
A general overview of the plug-in can be found in the Sun Java System SAML v2 Plug-in for Federation Services User’s Guide.