Bungie have been working on Microsoft hardware exclusively in the past. A natural course of action as they were fully owned by Microsoft between 2001-2008, but as they broke free and struck a deal with Activision, they need people with PS3 programming skills.
"Bungie is seeking a relentless code warrior, devoted to the pursuit of programming excellence and of furthering our ongoing quest for world domination. Bring your thirst for knowledge and PS3 might and fuse it with our talented team; together we shall forge a dread Engine that will quake lands (of many architectures) underfoot,"
Read the full job ad here.