Differences between Sproutcore and Ember

Question

I had selected sproutcore as a framework right before Ember forked from sproutcore. I am left uncertain of which way to go and a bit frustrated in the apparent dilution of efforts caused by the fragmentation - as rarely does that lead to better things. The efforts of Sproutcore 2.0 (now Ember) seemed to be going in the right direction of modularization and reuse of other javasript components (jQuery), however it is really unclear from an outside view why the two efforts had to split... couldn't we have modular code, and a widget library module too?

The main questions are:

1. What are the effective differences between the two efforts?
2. What is history of the split?
3. What is sproutcore future, where is it going now?
4. Is Ember going develop to be a complete replacement for sproutcore?