Hi Jan,
Re. your statement: "It turns out that the original Dutch version is in the public domain in Poland -- but not in the Netherlands"
This may be premature. It all depends on whether you accept the claim that Otto Frank has copyright over Anne Frank’s diary.
As I stated on the communia-blog: that claim has not yet been upheld by any court and is considered invalid by several experts on the writings of Anne Frank.
I am not sure whether this campaign - however sympathetic its cause - helps ensure that Anne Frank's diary remains firmly in the public domain, as it appears to take these claims for granted,
Also: the text of the diary has been available from this (French?) website since January 1.