Evolution is happening right now, and it is really, really ugly.

Darwinists rejoice: the cane toad, scourge of Australia, movie star, and all around nasty critter, is mutating.

Darwin's nightmare: Toxic toad evolves to secure supremacy.

Normally, evolution at the macro level does not occur at a visible level. This is a nice case because it shows evolution, natural selection, and adaptation in a species that has a high public profile.
Here's some background on the cane toad, from Nature:
Invasive species: The toads are coming!
If you're interested in cane toad biology, and it IS facinating, as well as the ecological impact of its introduction to non-native habitats, check out the movie Cane Toads: An Unnatural History. It is a hilarious and enlightening documentary about the importation of cane toads into Australia to control rats. Interstingly, the reason they didn't like the rats was because they were eating the sugar cane, a non-native cash crop.