Completionist cape

The Uber cape was first mentioned in the Capes of Distinction Developers' Blog. This cape will only be worn by players who have:
 * All skill levels at maximum (120 Dungeoneering and 99 in all other skills.)
 * All quests complete
 * All tasks complete
 * All magic spells unlocked (Spells from Livid Farm, Mage Training Arena, and the Mage Arena)
 * All prayers unlocked (Prayer from Dungeoneering and Camelot training room)
 * All Varrock museum Kudos
 * Miniquests:
 * Abyss
 * Ghostly robes
 * Shadow sword
 * Goblin High Priest
 * The Lair of Tarn Razorlor
 * Returning Clarence
 * Stronghold of Player Safety
 * Stronghold of security

Emote
http://www.youtube.com/watch?v=LMkkb5XqmQM&feature=feedu

Some previous inside information about this cape by Mod Chris on the high level forums:

As stated in the Developer's Blog, to keep the Uber Cape, the player must complete all new content released, similar to the quest cape.