Although this is not followed consistently, as a general rule, the making of pictures is forbidden in Islam. It is considered particularly offensive to depict Muhammad even though there is no verse in the Qur'an and no tradition in the most authoritate collections of traditions that even mention it.
The following articles discuss various aspects of the issue in detail:
In early 2006, some cartoons of Muhammad caused riots in large parts of the Islamic world, resulting in the destruction of embassies and even the loss of life.