Kinda neat to see a modern internet take on a classic cover piece for an animated episode. Only in 2011 would you see the words 'LOL' instead of the classic 'haha'.
I think this turned out groovy and your use of textures seem to add instead of overwhelm (not to mention Harley is looking slick!). The building lights seem off kilter though as your lighted squares aren't really lining up or have much order. Because they're so disjointed, it removes the building effect I think you were trying to achieve.