What are the chances that humans will be witness to evolution of a new species?

The definitive answer to creationists would be the development before our eyes of a new species. Nobody ever discusses this, so I suppose the likelihood is not considered great. I was thinking though that forces like climate change and the introduction of invasive species may create pressure for the formation of a brand new species. I am not talking about a new form of bacteria, but something macroscopic, perhaps a new species of insect.