The details are slim.
Lupin the 3rd
Detective Conan
Versus each other.
Theatrical roadshow event on Saturday, December 7th, 2013.
One trailer, full of awesome.
Savor, enjoy, and pray for a license or a Japanese release with subtitles.
This feature follows up the 2009 TV special that paired the two together for the first time in anime form and it garnered a huge rating back then, which made it all the more surprising it took four years for it to get here.