Unity3d 2.0 Engine is out:

http://unity3d.com/







You can make games for Mac, PC and Web-Browsers with this tool. It provides very good and easy-to-use editors and supports lot of scripting languages. The editors work on Mac only but some of the users even bought a Mac only to use this engine like you can see here:
http://entitycrisis.blogspot.com/2007/01/unity3d-evaluated-wow.html

Dont forget to check the demos. Their tropical island demo uses streaming similar like Oblivion to display tons of details with only little memory usage and short loading times.

Have fun while examining their websites!
Frank