Welcome to the iPad Forum. Hope you enjoy your stay.
Strange. Anyone else noticing this? I updated my iPhone to 5.1 and history still works on there. Haven't done my iPad yet, so can't comment on that.
Are you sure you are not in private browsing mode? If you are, the title bar and tabs will be black, and will not hold items in history. If not they will be blue. Here's where to change things around.