This is a win win win scenario.
SGC wins because (as Barry put it so well) it "helps SGC stay more competitive with PSA, and also adds to their bottom line as collectors resubmit cards for a second look."
The pro-slabbers win because they get what they were requesting for many years (ie. more options at the lower end of the grading scale, where a card's eye appeal can vary greatly).
And the anti-slabbers win because this give them more ammo to lob at the grading companies for being money-grubbing, clueless, unproffesional dimwits who get it wrong half the time.
Win win win!
edit: actually, the only guy who gets screwed is RGold and his awesome Red Heart Musial collection.