As additional followup, it looks like the patch submission to get Cinder iSER support into OpenStack's upcoming Grizzly release didn't make it in time:
https://review.openstack.org/#/c/24017/
That review is now listed as "abandoned", due to lack of activity.
Any chance it can be picked up again, so this makes it into the OpenStack Havana release?
[note - edited for better clarity]