Animal Rights. Where's the Boundary?

A few days ago the NY Times ran a piece entitled "Humanity even for NonHumans". Not trying to be a poser - I didn't read it because I don't read the Times. However, there's a Koinonia blog has a post "Animal Rights and the Imago Dei" by respected biblical scholar/theologian Walter Kaiser Jr. Lots to think about there. Here's a preview:

There is no question that we as human beings do have ethical obligations to not only our fellow beings, but also to those outside our species. That is not in debate, but the question is this: to what level and gauged by what standard of suffering, goodness, or pain do we express that ethical obligation?

Later in the same post:

Here is an area we must pay more attention to in the coming days, for the gap between mortals made in the Imago Dei and the rest of the creatures of creation continues to become so narrow that one will not be able to set any type of priorities or levels of importance among all the species except for the responsibility of one order of species (mortals) to be responsible to care for all the other levels of creation.