The team in this photo has been identified at the Library of Congress American Memory site and consequently elsewhere on the internet as the 1911 Chicago American Giants:

I probably don’t have to tell readers of this blog that these aren’t the American Giants.  Rather, they’re the Chicago Union Giants, as you can tell from the logo on their jerseys. 

According to Black Baseball in Chicago, by Larry Lester, Sammy J. Miller, and Dick Clark, these are the 1905 Union Giants, managed by William Peters, and the players are, from left to right: Bill Irwin, Willis Jones, Fred Roberts, Haywood Rose, Tom Washington, Harry Hyde, Clarence Lyttle, George Hopkins, Chappie Johnson, and George Taylor.

UPDATE 5/6/2011 New information from Todd Peterson on the Union Giants players in this photo.