I don't think the cartoon was meant as a caricature of Obama as a chimp, nor do I think it was racist (at least consciously).   The obvious (to me) message is "the stimulus bill was so poorly thought out that it might as well have been written by an ape."   (And in that sense, one might say some of the republicans who hammered out the 'compromises' might also be implicated.)

And you're right, Midchuck, that caricatures of a black person are more likely to be perceived as racist, in a white-dominated society, than are caricatures of whites.   But I think there are lots of ways to caricature Obama without seeming racist. (E.g., you could exaggerate his skinniness or his protruding ears, neither of which is a particularly "African" trait.)

More importantly, I think we do need to realize that some words and images that are not viewed as racist or 'ethnicist' in one context are likely to be in another. George Bush was caricatured as a chimp because of his individual facial features and because of how a lot of people perceived his smirking and snickering and his demonstrated intellect. It was not racist in his case, because anti-white European-American bias does not usually involve comparing their looks to simians or attributing lower intelligence to them.   Similarly, the cartoons depicting Lincoln and a monkey, while pretty vicious, weren't racist either.
But when there's a fairly recent cultural history of putting down blacks as lower on the evolutionary chain, comparing their looks to apes, etc., a cartoonist should know that if you use simian imagery to lampoon a black person, it's probably going to be perceived as racist.

One other thing.   It is especially insensitive and in poor taste to make fun of and incident that resulted in a woman losing her eyes and half her face and her friend's having to stab a beloved pet that she had raised like her own child and have the police shoot and kill him.
Can you imagine a scenario where someone's teenage kid goes berserk and savagely attacks their friend, with potentially lethal results, and the parent has to take a knife to their own kid and then watch the police shoot the kid dead?    Do you think a political cartoonist would use that scenario in the way this one did the police shooting of the pet who attacked a woman?