Viper supports all versions of MAC OS X 10.6 and higher with at least 5 GB of free space.  Viper also has a special app fo the iPhone which allows you to:

1) View all your documents from your backed up PC's and MAC computers.
2) Backup your iPhones contacts and pictures.  Your contacts are stored as VCF files, which can be opened with all your popular email applications.  This is useful, when you don't have time to sync with itunes.