There are a bunch of items that are listed on the Trash drop list that don't appear to drop from Mount Hyjal based on Wowhead/Allakhazam/Thottbot. While these are rare drops, one would imagine that at least one of the databases would have an instance of that item dropping if it truly did drop there. Is there other evidence that these items actually drop in Mount Hyjal rather than only in Black Temple? - Arianne 01/22/08
There is overwhelming evidence from the drops observed by Wowhead/Allakhazam/Thottbot that some Epic items appear on the loot tables of trash mobs in both Hyjal and Black Temple, while other items appear only on the loot tables of mobs in one instance or the other.
All of the "Rumored" items priorly appearing on this page drop only from Black Temple mobs (see link for Wowhead evidence): Band of Devastation , Blessed Band of Karabor , Girdle of the Lightbearer , Illidari Runeshield , Pillager's Gauntlets , Ring of Ancient Knowledge , Shroud of the FInal Stand , Swiftsteel Bludgeon , Treads of the Den Mother .
For contrast, here's an item that clearly does drop from mobs in both instances: Choker of Serrated Blades: 
Mattlistener 15:49, 31 March 2008 (UTC)