Slave labour: rmxd mentioned that Leica used them (I guess forced east european labour is somewhat the same as slave labour) in the 1940ties, I just assumed he knew what he talked about. Google gave me this:
http://www.jewishvirtuallibrary.org/jsource/Holocaust/germanco1.html
Regarding how authentic it is:
http://forums.dpreview.com/forums/readflat.asp?forum=1038&message=35629610&changemode=1
One guy say:
The story first appeared in 1999, after Leica was forced to pay compensation for its use of slave labourers during the war (along with several other companies). The facts are that Leitz was an important supplier of military equipment, including innovative research-based equipment like the guidance systems for the V2 rocket, it used slave labour, and Ernst Leitz II was a member of the Nazi party.
There is evidence that Leitz helped one or two people to leave Germany before the war, but there is no evidence to support the story that there was a "Leica Freedom Train" with hundreds of people sent to safety.
I say: I have no idea if the freedom train is true or not.