Don't get me wrong: I'm really happy with this tool because it gives people with a limited knowledge of English a chance to reach a broader audience, which is a very good thing.
I just vaguely remember reading a post (or maybe just the title of the post) some time last week about plagiarism through translation, and the thought just popped up in my head.
(Personally I don't have a problem with people translating quality articles. If it's good information, why not translate to share it with the world)