$599 at B&H for just a few days (until March 6th).
A quick check seemed to say the $100 savings is available at other retailers too.
This lens was $699 just a 10 days ago, went to $650, then down again to $599. I have been looking at this lens for a while, and have not come across many (really zero) mentions of discounts and savings. It has been going for $575 to $600 used.
Finally, my gear buying indecisiveness pays off!