Unity Engine

Saw this bit on MacNN about The Unity Engine:

Anyone will be able to easily develop games using a realistic and fast Ageia physics engine and a powerful new proprietary graphics engine to make games that work on both Mac and PC." Unity-created games can run in Apple's Safari web browser, or other select Internet browsers, and can also be exported as Dashboard widgets.

There is an indie license for $250. Looks fairly promising, so check out the product page.