The red channel has the cleanest face detail and the blue channel shows the most distress, so I eliminated the blue. Kept the green for its better detail in the dress.
Use the spot healing brush to eliminate the larger specks, then create a duplicate layer, blur to hide the smaller specks. Reveal sharper eyes, locket, mouth with a layer mask.
Convert the gray scale image, created by splitting channels, back to RGB and colorize for a sepia tone.
If desired, add a new layer and hand-color the image similar to the style of the time.
forum discussion: http://forums.dpreview.com/forums/read.asp?forum=1006&message=25636485
link to original photograph posted by Michael Stecker: http://mstecker.com/pages/steckMinnieWeissStecker_c1916b2.htm