Every week, there is a new mutation released on both PC and Xbox 360 for Left 4 Dead 2, but today's one (december the 3rd) is the most important to notice since it announces that community created mods is striving to make its way for the Xbox gaming with the next week's upcoming mutation:
"As we continue to update bi-weekly, we will be incorporating some of these community Mutations. To make a Mutation, you will need to build and test your mutation on the PC but we will release them on both PC and Xbox 360. So user created content is beginning to see itself on the Xbox 360!"
Update: The Left 4 dead 2 user created mods for mutations can be enjoyed by Xbox 360 owners ONLY after buying "The passing" DLC (and Left 4 Dead 2 of course).