Haven't yet, but will in my next campaign.
I was never a 2e Dark Sun fan. Planescape? Bought and played everything. Ravenloft? Bought and played most things. But Dark Sun always looked a bit too wacky for me. Bug-men and chitin armor and half-dwarves. Never bought any of it; never played any of it.
4e Dark Sun, though, has got me really inspired. The campaign setting book is good, and the creature catalogue is even better. My next campaign will be Dark Sun, and we'll be using the inherent bonuses.
Interestingly, I did something similar to inherent bonuses with the second 4e campaign I ran. We did a replay of the class Dragonlance series (every module: DL1 through DL14). If you've played the modules, you probably know they're very story-driven (yeah, perhaps too much so). There aren't many magic items and phat loots. So, I decided that each PC would begin play at Level 1 with two "legacy items". Sturm's sword and his armor, for example.
Instead of Sturm hunting down a choice new sword to nab off a fallen foe's body, his own ancestral blade would automatically "level up" at the end of each module (usually, every 2-3 PC levels). It might start as a +1 sword, then become a +1 vengeful sword, then a +2 sword, and so forth. Mechanically, it worked very similar to inherent bonuses, but it gave an added incentive to keep hold of your personal items.
It seemed to work well, which is why I have no fear of adopting the new inherent bonuses system. But I still think I'd reserve for "special" campaigns (like Dragonlance or Dark Sun). I'll continue to use the standard "phat loots" treasure system for traditional campaigns.