I'd say a combination of noise from high ISO (you don't get grain in a digital image, only noise), some noise reduction causing some of the blurring (maybe in camera?) and jpeg compression. Look at the tip of the pen, the way it seems to be smudged.
Make sure you are saving on the highest level of jpeg quality possible. In photoshop, this should be 12. I see a "JPEG 6" in your EXIF data. I don't know if that is a photoshop setting or the camera setting. If photoshop, change it to 12! If the camera, change to RAW, you will get better quality and much more control.
See the comment in this post from
Dvorjakusan for a good description of noise:
http://www.istockphoto.com/forum_messages.php?threadid=73672