Release notes for Ageia's latest PhysX drivers have let slip an interesting tidbit about a new feature Ageia might be cooking up for its physics accelerators. Accessible here, the release notes include the following information in a list of enhancements introduced by version 2.6 of the PhysX developer toolkit..Read more over here.
AGEIA working on PhysX 'SLI'?

AGEIA is apparently working on some sort of PhysX 'SLI'