Hiding the edges of the artboard is available in Adobe Illustrator, and I cannot recall, but I could swear it was available in earlier versions of Photoshop, under View menu. I Googled it and found no reference to it, but I knew it was possible. So I had a couple of hot tea cups (it does enhance intelligence and focus!) and looked through all options in Photoshop CS5. And found this:
Under preferences > Interface, set Standard Screen Mode : Border to None. Yippee!