Now, Hawaii scientists report they have successfully cloned mice. Their method is reportedly easier, and more consistant. Many years ago, similar experiments were tried with frogs, but there was some conflict over the accuracy of the results. Here's some links to more articles. The Sheep Cloning Paper from Nature, the scientific journal Nature main page.
Nature has password protection on reading articles.
You may have to sign up to read it online. Natures's Public Cloning Section, no password protection. The report on the Cloning of Mice . It appeared as a letter to Nature, not a full scientific paper appearently.