I've just upgraded from cryptsetup 1.6.4 -> 1.6.6. After the upgrade, I found that initramfs was not pulling in the binary(s) to unlock an encrypted root volume. This is happening now that 1.6.6 includes a fix to bug #714104. My /etc/crypttab had been empty until now. After adding an entry for root in crypttab, initramfs in now pulling in the cryptsetup binary(s). With previous versions, having an entry for root in crypttab was asking to unlock the root volume a second time later on in the boot process.

Just a heads up if anyone else runs into this.