From: http://en.wikipedia.org/wiki/Human_cloning
Human cloning is the creation of a genetically identical copy of a human. It does not usually refer to monozygotic multiple births nor the reproduction of human cells or tissue. The ethics of cloning is an extremely controversial issue. The term is generally used to refer to artificial human cloning; human clones in the form of identical twins are commonplace, with their cloning occurring during the natural process of reproduction.
There are two commonly discussed types of human cloning: therapeutic cloning and reproductive cloning. Therapeutic cloning involves cloning cells from an adult for use in medicine and is an active area of research. Reproductive cloning would involve making cloned humans. Such reproductive cloning has not been performed and is illegal in many countries.
A third type of cloning called replacement cloning is a theoretical possibility, and would be a combination of therapeutic and reproductive cloning. Replacement cloning would entail the replacement of an extensively damaged, failed, or failing body through cloning followed by whole or partial brain transplant.
Mammals have been cloned before. Human cloning isn’t an impossibility. As your text mentions at the bottom, human cloning is a theoretical possibility.
The last publicised attempt successfully created an embryo cloned from the somatic cells of an individual, but the embryo failed to implant inside a woman.
As mentioned earlier, mammalian cloning has been proven. Human cloning isn’t a very big leap, in terms of the technicality.