So, we played through the 3.5 version of the Tomb of Horrors. In one part there is a gem that grants a wish/nuclear fireball combo once/week. It seems like the gem is supposed to be bad for the players, being 'cursed' and such, and it certainly tries to pervert wishes more even than regular wishes, but it's actually rather extraordinarily useful. It seems odd for such a legendarily difficult module to just drop this thing in the middle of the dungeon, and our party ditched the crawl after our camp ID process demonstrated it's absurdly-above-our-party-level level of power. I definitely don't remember making out with infinite fireball-wishes from the original ToH, and I am wondering at what point the cursed gem of wishing was added.
Yes it was, but there was no way it could be described as "extraordinarily useful"
From the description of room 25.C. (emphasis mine):
The gem is a cursed wish magic item, and no matter what is desired by the character daring to touch it and wish, a reverse or perversion will bring doom to that character and all named in the wish.
It never does anything good: it always "bring[s] doom".
The 3.5e update complicated this (of course) but didn't change the essence:
The gem of cursed wishing grants a wish, but it perverts the wish made so that no matter the wish, the desire of the holder is perverted, reversed, or otherwise foully twisted such that the holder (and any other hoping to benefit by the wish) is instead hurt. For instance, wishing a friend back alive might kill another friend, or disperse the remains; the DM makes the final call.