Einstein had a much better analogy for mixed eignestates, and his version had no cat and did not involve potentially problematic metaphysical questions about whether there is a bounded Hermitean operator corresponding to "Life" or "Death." In his paradox, there is a keg of gunpowder in Schroedinger's Box. The question then becomes, when a quantum of radiation is introduced, is the gunpowder in an (un)exploded state or a mixed state of the two?
He argued that not even the most strident defender of quantum mechanics would remain in the room, secure in the belief that the gunpowder was in a mixed combination of eigenstates until the box was actually open.
That paradox is stripped of the silly aspects of the Schroedinger's Cat paradox, but for the same reason did not catch on in the imaginations of popular science writers who don't really understand science very well.
Assuming something that I don't believe -- that there's a quantum mechanical operator corresponding to "Life" -- for the purposes of advancing a hypothetical, if you could find a complementary physical property for a two-cat state, flipping that state in the near cat could kill the remote cat and bring the local cat back to life. Flipping that eigenstate again would bring the remote dead cat back to life, and kill the local one.
This is instructive in the instant case because no one believes physics can bring a dead entity back to life once truly dead. A perfectly good alternative explanation -- precisely because the two cats are indistinguishable -- is that you have merely teleported the dead cat to the live cat's former location, while teleporting the live cat back at the same time.
What convinced me that the state vectors really don't collapse until observed is the experiment with a laser pointer and three polarized sun-glass lenses.
Point a laser at a piece of polarized stuff oriented up. This will cut the intensity of the beam significantly by filtering out everything that isn't polarized up.
Downstream of that put another polarized piece oriented sideways (90 degrees) from the first piece. Given a sufficiently good quality of polarization this will pretty much totally stop the beam. This is all in accord with everyone's experience.
Now, what happens to the downstream beam (currently totally blocked) if we insert another polarized piece oriented at 45 degrees between the existing two? If the polarized pieces were just acting as filters the intuitive result would be exactly nothing.
This is not what happens. What does happen is that where there was darkness downstream there is now a pretty good beam. What happens at each polarization stage isn't a simple filtering, it is an honest to God observation, and it really does alter the polarization of the incoming photon.
I, for one, welcome our new Observing Overlords /.