The same thing happened to me right after I got my macbook. I used NON-ACETONE nail polish remover, and that got most of it off, all except a tiny bit on the edge and a very light shadow in its original place. Within a few weeks, that had disappeared, too.
The strange thing is, I couldn't figure out how I got the ink there. But I'm a teacher and writer, normally covered in ink, so I figured I had just somehow been careless. Then, a few weeks ago, I read a thread where several people were saying that blue ink had mysteriously appeared on the palmrests or trackpads/buttons of brand new macbooks -- and most of them also reported that it disappeared a few days to weeks later, as mysteriously as it had come. If you're not sure how the ink got there, look for that thread! Strange as it sounds, it was definitely my experience.
