"ICC raid gear"
"Green Cata items"
Sorry: basic terminology time.
"ICC" = Icecrown Citadel. The 'highest level' raiding instance in the previous expansion (Wrath of the Lich King). When people say "ICC epics" they're generally referring to the best possible items (gear) you could get in the previous expansion.
"Greens" = relatively common items. Each grade of item is color-coded (I assume you know), indicated by the color of the item's name. Gray items are trash, white is common, green is uncommon, blue is rare, purple is epic, orange is unique.
Gray items are junk that is dropped from stuff you kill. White items are generally bought from vendors or gathered for use in crafting. Green items are usually quest rewards or drops from common enemies. Blue items are rewards for tougher quests, dropped in the world from rarer enemies (sometimes) or dropped by boss monsters in dungeons. Purple items - epics - are generally dropped by end-game raid bosses, or are purchased with certain currencies (used to be badges / emblems; now "Justice Points" for PVE gear, or "Honor Points" for PVP gear.) Epics are generally the highest quality items you'll have and are usually only available when your character is at the level cap. Orange "unique" items are extremely rare and most players will never own one.
Gold is "heirloom," a special type (also known as "BoAs," which means Bind on Account) that is purchased by a high-level character and gifted to your low-level characters; unlike most other items that are "soulbound" to a specific character, the heirloom items are bound to your account - meaning you can send them via in-game mail to any of your characters on a specific server, including Horde or Alliance.
EDIT:
Basically, my lament was this: the items ("ICC epics") that I earned by battling the toughest monsters in the game (at that time) with 9 or 24 of my stalwart compatriots, over and over and over again over many months are now null and void. They are being replaced by items ("Cata greens") that I'm earning by completing "fetch me 10 squirrel tails" quests in the new Cataclysm expansion, which take me all of 5 minutes to do by myself with zero effort. Make sense? Good.
