According to the Islamic Republic of Iran's "merciful and compassionate" implementation of the Sharia, adulterers must be stoned to death. So yes, in the 21st century, we are still seeing cases of it. Here's the latest, courtesy of Raw Story.
Here's a quote:
Under Iran's Islamic laws, adultery i[s] the only capital offense punishable by stoning. Other capital offenses in Iran include murder, rape, armed robbery, apostasy, blasphemy, drug trafficking, prostitution, treason and espionage.
The punishment is also applied in some other countries such as Saudi Arabia, United Arab Emirates, Sudan and Nigeria.
A man is usually buried up to his waist, while a woman is buried up to her neck. Those carrying out the verdict then throw stones until the condemned dies.
Obviously, murder can't be as evil as adultery, because murderers are merely hanged, beheaded, or stood up before a firing squad. And if you are an "apostate" or a "blasphemer," we will also sentence you to death. Adulterers, on the other hand, get to savor the unique agony of having stones hurled at their head and torso. And then there are the "merciful and compassionate" folks who have the special privilege of gathering around the victim and throwing the stones.
Now you can qualify this all you want--the punishment isn't applied that frequently, the judgments were in regions with low rates of literacy as opposed to sophisticated Tehran, etc. But it doesn't change the fact that the countries listed above actually have stoning officially on the books as a punishment--and for adultery, no less. (Correct me if I'm wrong, but I believe only parts of Nigeria use the Sharia.)
What, isn't divorce good enough? How about a scarlet letter "A"? No, we must have stoning--that is what God's merciful and compassionate law requires.
You can read more about Iran's peculiar concept of justice at Human Rights Watch's lengthy section on Iran.
Religious barbarism is still very much alive and well in all corners of the globe, it seems.