I realize this is an old thread, but perhaps people are still reading it looking for ways to do this. One way to smooth out scanned calligraphy in Photoshop is with the "Stamp" filter.
You can select this filter from the main menu. On my older version of Photoshop, it's under Filters/Sketch/Stamp (and it's probably in about the same place on newer versions). When you select the Stamp filter, there are two sliders that you can adjust: "Light/Dark Balance" and "Smoothness". Play with both sliders to find the look that you want. (You can really crank up the smoothness, but if you do that too much, you're liable to lose some of the thinnest lines in your calligraphy.) It's a simple technique that only takes a minute or so, and it can of course be combined with other touch-up techniques.
For example, you could apply this technique to the mask that I describe in the "Scanned calligraphy in Photoshop without the Magic Wand" thread, rather than applying it to your calligraphy directly. In my experiments, this seemed to give slightly nicer results, but really both methods seem pretty close.
I'm attaching three images here: an image of some scanned calligraphy, another image that I got by applying the "Stamp" filter to it directly (with the black background that was created in the process), as well as an image that I got by applying the "Stamp" filter to the mask that I describe in the other thread (this image has a white background that I made using the method that I describe in the other thread).
