You think you've got problems... thanks to the Sonny Bono act, nothing in the U.S. will enter the public domain by default till 2019.

(I say by default since an author can deliberately release a work to the public domain.)

I don't know what the "right" length would be -- I'm not so devoted to rights to atoms (physical property) as to exclude rights to bits (intellectual property). 70 years after the death of the author does seem a bit lengthy.