Hi Matthew,
how many photos from WLM 2012 have already been incorporated in Wikipedia
articles (total and by country)?
Same number than Arild using he tool pointed by Andrea: (In main namespace only: Distinct files used = 48,998 (13.3% of all files), Pages using files = 15,377 ; Total file usage = 59,917)
Also, how many monuments that didn't have photos before have photos now
(total and by country)?
See < https://commons.wikimedia.org/wiki/Commons:Monuments_database/Statistics%3E
and make the diff with the revision before September 1st (though obivously monuments lists will have been improved during that time)