Tech Crunch is reporting that MakerBot is now shipping the Z18 printers which have been on pre-order until now. This follows the shipping of the Mini's a few weeks ago, and the Replicator Gen5 since March.
MakerBot recently stopped selling the previous generation Replicator 2 (although the 2X is still available). Perhaps this is a sign that MakerBot is feeling confident about their new Smart Extruder.
It also appears that you can no longer buy 1.0 kg spools from MakerBot. Instead, their "large" spool is 0.9 kg, and may be more difficult to fit on the Replicator and Replicator 2X when using two spools at a time.