Another real handy thing to have around is Funtak, or some similar clay-like substance. Best to find one that leave no residue behind, but they all do to some extent. You use this stuff to prop up unbalanced devices, or to raise the subject off of the surface of your white background paper.
And you all thought that I made the phones levitate when I photographed them....
What this does for you is twofold. Firstly, you can use it to soften shadows, as seen below. The shadows are present in both shots, but they are much softer in the top shot because the phone is raised off of the paper's surface with the funtak.
Additionally, you can use carefully placed pieces of the stuff to take shots that make the subject appear to float above the surface of the paper. This looks pretty cool, but is sometimes difficult to do. Open clamshell phones can be real hard to do like this. And always make sure that the funtak is not visible in the photo. For those of you not using an SLR, remember that the camera lens has a lower vantage point than your viewfinder, so it will see further under the phone to where the funtak is. Be warned.
Top is with funtak, the bottom is resting directly on the paper