Looking at the new (late 2008) macbook/mbp taken apart by iFixit, it seems like painting the one aluminum cover black would do the trick. This should be far cheaper and easier to do than the process Colorware charges so much for.
Must be cheaper options out there to paint one chunk of aluminum.
Does anyone know if painting it (or gluing crystals on it) will void the warranty with Apple, or at the very least, cause you problems if you need to send it in for something?