Tonight Anne, our new lore columnist, did the 25-man version of Securing the Ramparts, and she reports back that the frost giant (a special mob that appears only for the quest) was "friggen HARD" and that although they got it in a couple of tries, a PuG might have trouble. There was an interesting fight mechanic in the form of a disease debuff that must be passed to another player within 30 seconds, or else it kills the target. The original target is now immune for 30 seconds (no tagbacks, I guess).
The giant dropped no loot, but for completing the quest you get Sack of Frosty Treasures, which contains 5 Emblems of Frost, some gold, and a chance for epic gems. Has anyone else had a chance to try the new weeklies yet?