I just have read on a similar french web forum that L.A. Noire was going to be multiplateform too ...
Does someone have a web link to confirm or not this ?
EDIT : http://www.gamesindustry.biz/content_page.php?aid=25852
L.A.Noire multiplateform confirmed ...
==> 2, more or less exclusive, system seller for Xbox360 : Bioshock and GTAIV ...
(Halo3 is just sequel to the "notbad" sequel,Halo2, of a system seller Halo1 : most people who want to play H3 have already a Xbox360)
Time to Work !