We too have heard some rumors ...
... about it being something in the vicinity of a "new storage system build by IBM" (not OEMed like the DS3/4/5k series) with some connection to the SVC. Sadly, no more in depth infromation was available.
To take a wild guess, i could imagine attaching a more dumb storage array to the SVC, while moving some of the array controller logic - like classic RAID or a XIV-type chunk based RAID - into the SVC.
If they'd also drop the outrageous SVC volume licensing prices by a significant portion we'd definately be game!