If you already know how to do this, I apologize. I just thought I'd let people know there's an app that actually successfully erases the market history! I found it last night when I was trying to find a way to delete my "Frequent Calls" list (Worst thing ever!). It's called HistoryEraser. It successfully erased my entire Market History. It also resets frequent calls, google maps searches, call logs, and browser history. Enjoy.