First they came for the funny ones:
Ahhh... finally, the back-story.

"The cartoonists in question are a dozen Danish artists who drew Muhammad-themed cartoons last September for the Danish newspaper Jyllands-Posten during an exercise to test the limits of free speech. The cartoon-a-thon was conceived in response to complaints from a Danish author who couldn't find anyone to illustrate her Muhammad children's book.

Although the book itself was not controversial, the Muslim faith considers it blasphemy to depict the Prophet in any way. Thus, in December, the youth branch of Pakistan's largest religious party, Jamaat-e-Islami, offered a bounty for murdered cartoonists. "