How do your rearrange the photo album icons in Photos for iPad?
First, there is no way to move the "Camera Roll" album and the "My Photostream" album. These two albums are always at the top and in that order.

To arrange any other albums, including the automatically created "Videos", and "Panoramas" just tap "Edit" in the upper right corner. You can now tap (hold) and drag these albums around as you desire. They drag and drop in the same way that your home-screen icons do. When you have adjusted them as you like, you can tap the done button.