Most people told us to stick with Amber.js, but a sizable minority told us to come up with a different name. After thinking about it, we didn't feel good about the conflict and decided to choose a new name.
Henceforth, the project formerly known as SproutCore 2.0 will be known as Ember.js. Our new website is up at http://www.emberjs.com
(and yes, we know this is pretty ridiculous)