Pharo is a pure object-oriented programming language and a powerful environment, focused on simplicity and immediate feedback (think IDE and OS rolled into one).
Pharo is open-source under MIT license. Pharo is used in more than 25 University worldwide http://pharo.org/Teachers. Books on Pharo are available at http://books.pharo.org. Check the Pharo success stories at : http://pharo.org/success.
Pharo is partly developed by RMOD.