Best answer by Jon
Tenative target is first half 2017, but again, that's target, and dependent on all phases of engineering signing off (design, engineering, QA, etc). As you know, GovCloud is not the same as regular ole AWS, so we've got to make a few enhancements to properly work with GovCloud before releasing it to the masses.
We're tracking this internally with engineering ticket FEAT-2109. If anyone (you or otherwise) files a request for enhancment (RFE) support ticket, please reference this ticket number so we can associcate that RFE to the engineering system. This helps us track customer demand.