This blue iLevel = 187 tanking cloak is better in almost every way than an epic iLevel = 200 cloak from Maexxna.http://www.wowhead.com/?item=44188
They should likely be considered equivalent (that is, the Cloak of Peaceful Resolutions should have an effective iLevel of 200, though not necessarily considered purple). This item is best in slot for tanks until Naxx 25 (or 25 valor emblems), when the upgrade is iLevel 213. In the interim, even tanks who have Cloak of Armed Strife are taking a rating hit by choosing to use the better (blue) cloak.
The Seal of the Pantheon, a tanking trinket from normal Loken, is best in slot for many tanks, once again until Naxx 25. It's technically blue and iLevel 187, but it should be set as effectively iLevel 200 with its ridiculously high +def rating (+13 def skill! Almost 10% needed for def "cap") on a trinket. Since there are no superior trinkets at iLevel 200 (the upgrade is from Naxx 25), this should be considered 200.http://www.wowhead.com/?item=36993
And finally, the Essence of Gossamer really remains best in trinket slot for almost all tanks, with a whopping +111 Stamina on a trinket and a really great proc. iLevel=200 is probably fine, but considering this effectively an epic item would better weight the rating to reflect its crazy usefulness.http://www.wowhead.com/?item=37220