Update! Click here (Zoom, Pan, and Navigate Documents in Photoshop CC) to see all zoom, pan, and navigation tips for Photoshop CC in one post.
When viewing multiple images simultaneously, Shift -drag with the Hand tool to pan all open documents. Similarly, shift -clicking with the Zoom tool will zoom all images simultaneously. To set this as the default behavior, with the Zoom or Hand tool selected, check the “Zoom all Windows” and/or “Pan all Windows” in the Option bar.