There many ethical issues with cloning, and genetics in general.
In the United states, many supermarkets are already selling Genetically Modified foods. Most of the produce usually creates its own pesticide that will eat the insects from the inside out, a trait borrowed from a group of bacteria that, to our knowledge, has no adverse affects on humans. The ethical issue comes into play here: most supermarkets do not advertise these foods as Genetically Modified. Even though no adverse affects are known to date, not allowing the customer to know that they are purchasing GM foods is controversial. There are two main sides of the argument:
1) GM foods won't harm you, so why tell the people? If they have adverse affects once you tell them, it could be a self-fulfilling prophecy.
2) Even if it won't hurt us, you should still tell us so we have a choice in the matter. That's like giving us a certain drug without telling us: it's not ethical.
If you go into your local supermarket and ask the General Manager if they know whether GM foods are being sold, the answer will probably be a resounding "No", since there is no separate signing for these foods. This reflects an underlying problem with the genetically-modified food discussion. Which foods are genetically modified? Many seedless fruits exist as a result of primitive genetic manipulation in the form of accelerated artificial selection. Products such as corn and apples could not exist without human intervention in the form of breeding and cross-species grafting. If we place the boundary at the laboratory door, we demonize certain foods that have saved billions of lives, specifically golden rice and others with which we have become perfectly comfortable.
The main issue with the w:genetically modified foods is that their long term effect on the Earth's ecosystem is unknown. To improve a plant by natural selection took a long time and there was time for the ecosystem to adapt.
Cloning endangered species may be a good idea to keep the ecosystem in balance.