I don't know anything about that photo but there is another that might
interest you.  It shows Twain in bed reading a newspaper article about
Gorky.  A photo of Gorky is visible in the newspaper Twain is holding.
The photo of Twain is by Underwood & Underwood and was published in
the April 28, 1906, issue of the Literary Digest with two others showing
Twain in bed.  A scan of the photo is online in:

Mark Twain and the Gorky Debacle
http://marktwain.about.com/library/weekly/aa051397.htm

Jim Zwick