Yes, the patch includes a guild system. And that's not even the biggest part of the patch. It includes a new character class for players who have cleared the game on Normal difficulty, six new world areas, achievements, new skills, new items, and an assortment of balance tweaks and improvements. That's not even touching upon new challenge leagues and the like. The point is that even if you know the game inside and out, you might want to hop in tomorrow and try out the huge array of new options available to you because... really. There's lots of stuff here.