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I've been working on a series image for our summer series, "Fail Whale".  Obviously, based on twitter's (or yiying lu's) fail whale concept.  But, I have no idea if it is legal to use the image in my design and to what extent I can use it without infringing on Lu's rights.  

This is a specific example in a big picture issue that has been bugging me for a while.  Does anyone know of any good resources I can access that will help answer some of these questions?  

Thanks!