So...Nope, it really is Cover. Really. With a capital "C". Not some kind of flavor text put in that just happens to conincide with official terminology.
<EDIT> But I did mis-quote the save bonus, didn't I? Anyway, the way it jives with what we've been saying about Fireball is this: Cover does not protect against spreads (only bursts?), therefore the +3 Ref bonus confered by shieldis not applied to fireball saves.
We are both right, I remember reading somewhere either in the errata or what the sage said, think it was something the sage said since I can't find it in any of the errata, but the shield doesn't give actual cover, just "cover" bonuses. Still searching for it also where he said it. I could be wrong but I am pretty sure it isn't actual cover.