I've never seen a corner-grounded delta used, but I have seen a lot of floating deltas on numerous switchboards. Naval ships use floating delta exclusively- even for single-phase circuits, both wires are "hot" legs of a 110/63V Delta. The idea is that if there happens to be a single phase ground fault, it won't interrupt power to the loads, and the worst a single-phase shock could be is 63V, which is especially important when you might be half-submerged in salt water at the time. I see it a lot in buildings, too, even some floating wye (with X0 ungrounded)- the reasoning is always the same; that a ground fault won't cause an unplanned outage.
So, when I hear talk of corner grounding a delta, I immediately think "Ground Fault!"
