Ask HN: My app's been copied. What do I do?

We've had a very successful iPhone app on the market for the past 2.5 years. We've been planning on releasing an Android version within the next 4-6 months. However, today we found out that somebody in the Android Market has copied our app almost identically. They released it about a month ago. It copies our layout EXACTLY, our functions, our look, even graphics look similar. Now, this isn't a sort of copy, it's almost an identical copy. If it was just 60% of our app that was copied, that's one thing. But it's 99% of our app that's been copied. I'm concerned that our iPhone users who switch to Android will be confused that we made the app, and also that it will hurt our future Android endeavors. So, what can we do about it? Can we send a cease and desist? Are there any laws to protect us?