It seems a number of people are piling on to the Brownback-Landrieu hybrid cloning ban. Current technology limits our ability to clone or mix tissue from different species. Current limitations are profound. Scare tactics about creating a slave race of manimals are just plain silly.
That said, what is wrong with altering the human species in ways we decide for ourselves? People do all sorts of funky piercing and tattoos. Augmentation in the form of organ replicas (organic or not) are becoming more common. If we can control the outcome with surety, why shouldn't we make ourselves smarter or more resistant to disease or longer lived through genetic manipulation? Likewise, why are people afraid of hybridization with machines? What's wrong with merging humanity and machine into a cybernetic super-species?
Sure, there will always be ethical questions such as is it morally right to raise a creature simply for the service of ourselves? We may be morally bound to not cause undue suffering or humiliation to our creations. But how does creating the species change the same moral questions we face today about slavery or experimentation on living creatures or even just raising creatures for meat?