It was my understanding that SB-E got delayed due to a number of reasons:
 
1. PCIe 3.0 spec being late and unable to test properly.
2. X79 chipset issues.
3. PCIe bug on the C1 stepping which will require a C2 stepping in Q1.
 
Now if Intel can clear all these issues up by Q1, as they predict, then IB-E will just be a die shrink and should be on time for Q3. Of course that all depends on how well IB performs (issues?) in Q1.