It's always fun for geeks to peruse the ads that are placed by the big tech firms looking for help in specific areas. The ads and the sort of people that they are looking to hire hint strongly at features that are going to be added to various products. Microsoft had a new ad up a few days ago that was seeking a new worker for the windows Phone Backup, Migrate, and Restore team.
The ad doesn't come out and say that the backups will be done using the Skydrive cloud, but that would be a safe bet. The ad is seeking someone in the Redmond area to "help users restore their wiped phones to their user-customized states."
The backups could be done using the Zune interface on the user's computer too. I think the cloud option makes more sense so the user can restore and back up when they are away from the computer. That sounds like a great job for Skydrive.