Scientists at the Kharkov Institute for Physics and Technology in Ukraine have achieved what seemed to be a dauntingly impossible task: they've managed to take an image of a single carbon atom's electron cloud:
This is the first time scientists have been able to see an atom's internal structure directly. Since the early 1980s, researchers have been able to map out a material's atomic structure in a mathematical sense, using imaging techniques.
Quantum mechanics states that an electron doesn't exist as a single point, but spreads around the nucleus in a cloud known as an orbital. The soft blue spheres and split clouds seen in the images show two arrangements of the electrons in their orbitals in a carbon atom. The structures verify illustrations seen in thousands of chemistry books because they match established quantum mechanical predictions.
Link - via Derek Lowe's In the Pipeline