If you go to penny arcade, they have some of Todd Goldman's 'work' compared to other people's art that he allegedly stole from. They all look fairly similar, so it looks like this isn't just a one time thing.
Can I ask one thing? What's the difference between a homage and outright theft? What makes it OK for Mel Brooks to make Spaceballs, Weird Al to make Eat It, or for VGCat to make their delightful (and far more entertaining) version of 300?