This just in from Mark Sonntag:
[I stumbled across the UNIVERSITY OF MISSOURI's online photo archive and found these in The Baron Missakian Collection, the rest of the images on the site have been seen before.]
Nadine Missakian's, the Baron's wife, was Walt's secretary during the Laugh-O-grams days. Check Walt's People - Volume 5 to read an interview with her.
The archives left the above photo unidentified, but it is clearly Walt on the left.
Photo of Ub Iwerks on the set of MARTHA.