These cartoons have been out since last September. Why the fuss now? Very simple.
The Saudi government is creating a diversion to draw attention away from the fact that 350 people died during the Hajj, in the same place and for the same stupid reason as in previous years. The whole event was poorly organized, under-staffed and badly run. And Muslims died because of it, as they have in previous years, because the Royal Family did nothing to improve conditions, even after promising to. So in the aftermath of the Hajj tragedy, which was I reckon a bigger deal in the Arabic and Muslim world than over in the West, Saudi government controlled papers start making lots of noise about some stupid cartoons. And now we have this.
The claim that any depiction of Muhammed is offensive is stupid. There are icons and other objects, rugs even, for sale in Iran (as in, the Islamic Republic of,) that have Muhammed on them. He's been shown in countless works of art, including one in the US Supreme Court. It's a cover act, and a remarkably effective one. Muslims feel reighteous indignation, Europeans see Muslims masses rioting for the second time in six months, everyone goes home pissed.
edit: besides which, I was disappointed that none of the cartoons were either funny or offensive. At least if you're going to have several hundred million people pissed over something, it might as well be for something good, like Muhammed getting it on with a young boy or something like that. I can't even get a proper entertainment kick out of this.