First, wild talents on Athas as they were in 2nd Edition D&D.
Every player character was a wild talent. Unfortunately, due to the way wild talents were rolled in 2E, the outcome of the rolls could be disruptive. No doubt DMs had to curtail or curate what wild talents were obtained.
3.5e handles wild talents differently, and is actually a far better fit for Dark Sun. Instead of manifesting powers, wild talents are as described in this feat.
WILD TALENT [GENERAL]
Your mind wakes to a previously unrealized talent for psionics
Benefit: Your latent power of psionics flares to life, conferring upon you the designation of a psionic character. As a psionic character, you gain a reserve of 2 power points and can take psionic feats, metapsionic feats, and psionic item creation feats. You do not, however, gain the ability to manifest powers simply by virtue of having this feat.
Hidden talent is a feat that is closer to the 2E wild talent feat.
HIDDEN TALENT [GENERAL]
Your mind wakes to a previously unrealized talent for psionics.
Prerequisite: This feat can only be taken at 1st level.
Benefit: Your latent power of psionics flares to life, conferring upon you the designation of a psionic character. As a psionic character, you gain a reserve of 2 power points, and you can take psionic feats, metapsionic feats, and psionic item creation feats. If you have or take a class that grants power points, the power points gained from Hidden Talent are added to your total power point reserve.
When you take this feat, choose one 1st-level power from any psionic class list. You know this power (it becomes one of your powers known). You can manifest this power with the power points provided by this feat if you have a Charisma score of 11 or higher. If you have no psionic class levels, you are considered a 1st-level manifester when manifesting this power. If you have psionic class levels, you can manifest the power at the highest manifester level you have attained. (This is not a manifester level, and it does not add to any manifester levels gained by taking psionic classes.) If you have no psionic class levels, use Charisma to determine how powerful a power you can manifest and how hard those powers are to resist.
Note: This is an expanded version of the Wild Talent feat, intended for use in high-psionics campaigns.
In the 3.5e version of Dark Sun (published here at Athas dot org), player characters do not automatically get a wild talent. I think they should. Not hidden talent, just wild talent. The ability to take psionic feats is a good indicator of a character with some mote of psionic ability, but not enough to manifest a power.
PCs that meet the prerequisites could have other options. Instead of being a wild talent, their minds might resist psionics altogether. Such a character, meeting the prerequisites, could be allowed to have one of these feats applied for free at 1st level.
Hostile Mind [General]
Your mind recoils violently against those who use psionics against you.
Prerequisite: Cha 15.
Benefit: Whenever you are subject to a power from the telepathy discipline (regardless of whether the power is harmful or beneficial to you), the manifester must make a Will saving throw against a DC of 10 + 1/2 your character level + your Charisma bonus or take 2d6 points of damage.
Type : General
Source: Expanded Psionics Handbook
You are anathema to psionic creatures and characters.
Prerequisite : Con 15.
Benefit : When a foe strikes you in melee combat, the foe immediately loses its psionic focus, if any.
Also, if you are the target of a power, the manifester of the power must spend an additional number of power points equal to your Wisdom bonus, or the power fails (all the power points spent on the power are still lost). This extra cost does not count toward the maximum power points a manifester can spend on a single power.
Special : You cannot take or use this feat if you have the ability to use powers (if you have a power point reserve or psi-like abilities).
Incidentally, The Paizo version of Dark Sun by David Noonan implemented a more convoluted version of wild talents for some PC races.
That said, Noonan deserves praise for his boldness in giving some of the PC races a psionic ability. I would change Noonan’s version by giving humans (and the other PC races listed as having ‘inborn power’) the wild talent reproduced earlier. Noonan’s decision to give an ability bonus to humans is also a good idea.
I wonder if we can produce a revision of the Dark Sun Core Rules for 3.5e in 2022.