Answer honestly now: who actually kept the Luffa? The Luffa is a pretty much worthless trinket (except maybe for Rogues who often fight Druids or Warriors) available at level 49 from a quest in Searing Gorge. All it does is remove one bleed effect. It's not a bad trinket when you get it at level 49, but after that, more and more trinkets show up that do so much more that for most players, the Luffa ends up either in the bank, or, more likely, vendored away.
I know I sold it. But those of you who hang on to everything you find in the game have a reason to celebrate: the Luffa is back. Apparently in Karazhan, there's a rogue boss named Moroes who lays down a debuff called "Garrote"-- it's a whopping 1000 damage per 3 seconds for five minutes (or until he dies, as of 2.0.6), which is a lot of damage. And yet, while Stoneform, Divine Shield and Ice Block will all remove it, the only other way you'll get it off is, you guessed it, the ol' Luffa.
If, like me, you did vendor it, don't worry too much-- the Luffa only works sometimes, and the fight's not impossible without it anyway. But a few players are feeling a little regret at tossing away something they'd never thought they'd need. Maybe a future quest in Outland will someday grant us an extra absorbent Luffa for future use.
Update: And here's even more reason to keep it. Commenter Wari asks about Rokmar the Crackler's debuff in the Slave Pens (he drops a bleed that does damage until the player who has it is healed to full), and it looks like the Luffa will clean that annoying buff off too. Who knew the Luffa would be so useful?