At least, new to me, though I had read of its development in a book on stopping power. It's Federal's Guard Dog apparently only in .45 ACP just now.
It looks like an FMJ, but the jacket of the nose has four slits inside it, running up to the nose. The core is lead at the rear, with a wad of polymer in the nose. On impact, it deforms and the jacket splits along the slits. It gives quick expansion, near 100% retained weight, and no problems with a hollow point plugging up when going thru a barrier or through heavy clothing.
UPDATE: here's a review. He mentions one other advantage -- if you are so unfortunate as to live in a state that bans hollowpoint ammo, you can still own this.