Enable certain Vobjcets to send and recieve messages (via VOS messaging) to the host operating system's IPC system (e.g. dbus in Gnome/Linux, services in OSX, COM-or-whatever-they-call-it-these-days on Windows). Maybe as a site extension with selected vobjects flagged with a type?
TODO add resources for OSX, Windows, Gnome to this page, Example scenarios.
Or, at another level, write bridge programs that use libvos. E.g. to make "Automator" actions on OSX you write a little script or program that communicates with the application. That little program could use libvos to do it? (Need to investigate Automator actions more).