A video of a supposed "Mars Base" found on Google Mars has been burning up the blogosphere. Unfortunately, it is not an image at all, but a digital imaging dropout caused by long distance transmission. Image files contain a certain amount of redundant data that's used for error correction. When the data stream loses its integrity, the error-correction algorithms retrieve this redundant data and attempt to reconstruct each block. If there's not enough extra data to provide a complete reconstruction, what will result is a partial or "confused" reconstruction. That's what you're seeing in those blocks that are both lighter and darker than the surrounding areas. (The lightest areas represent a complete absence of useful data.)
In trying to interpret these kinds of images we have to distinguish between what our eyes are actually seeing and what our minds may project. When you're trained in photography one of the many things you notice (that most people don't notice consciously) is the behavior of light. Light from a single source (in this case, the Sun) throws shadows in only one direction -- but in this case the lighter blocks are surrounded by darker blocks in all directions, so they can't be shadows cast by a three-dimensional object.