Not only is it being officially acknowledged that the mass execution of Polish officers and civilians in Katyn and other places was actually done by the Soviet Union (more of that anon) but it seems that certain FSB documents indicate that Raoul Wallenberg may have been alive after his supposed execution for crimes unspecified.
This is not actually quite as suprising as Bruno Waterfield seems to think but then he, apparently, believes that the Wallenberg was arrested by the Soviets because of his supposed involvement with the American wartime secret service. I am not at all sure it has been acknowledged by anybody and the evidence for it is dubious to put it mildly. Could the arrest have had something to do with the fact that it was now the turn of the Soviets to commit atrocities in Hungary (and other countries) and they did not want an honourable witness whose word would be believed around? Just a suggestion.