I've noticed this effect not only in nocturnal carnivores but also in
white-tailed deer. I missed hitting many a deer coming home at night
because of this phenomenon. The deer's eyes appear a yellowish/green. So,
I don't think this is just limited to one type of animal. I've also
noticed this effect in pictures of my cats and dogs. With the colors
corresponding pretty much with what has already been said.
To tie-in the focusing effect and the alligator remark I can remember being
in the Evergalds and shinning a flashlight across the surface of Eco-pond
to see the 'gators that were floating around by catching the reflection off
their eyes. The interesting thing about that was if you were not the one
holding the flashlight you pretty much couldn't see the reflection. So, at
least for 'gators, this focusing effect is quite profound.