Yeah, and the Schwerin lion have also seemed to adapt and started to kill the meerkats, like I already mentioned...
@Taccachantrieri: I'd say it depends on the animals (and their value) involved and the reactions of the visitors...
There are some people, even mentioned in "Ethics on the Ark" who propose that in the case You have animals You want to reintroduce, it'd advisable to let them go through a "survival/boot camp" scenario where they are also confronted with prey and natural predators-even if that meant animal losses. Critics of this suggestion point out that this might end in a cruel & unfair massacre, which, due to the restrictions of the exhibits, would not resemble the conditions in the natural habitat. This is still a heatly debated subject.
About the immersion of prey/predators closeby, but not within the same exhibit, I do think the chronic stress aspect is important to be observed (after all, You too wouldn't feel at ease if You knowingly had to live next to Dr. Hannibal Lecter...)as well as triggering panic & flight behaviour should be avoided, but I have also seen a few combinations where it worked, as the animals got accustomed to each other. However, the negative impression on the average zoo crowd by this peaceful "Disney"-like scenario mentioned by Taccachantrieri should not be neglected either; it could help if surplus ungulates of the closeby exhibit would be fed as whole carcasses to the big predators, like Nuremberg or Munich Zoo do, to underline that these predators are no tame & friendly cartoon characters, but dine on their "neighbours" in the wild.