I've had this discussion with Microsoft Support in June 2014. They told me that backups are performed on all site collections on a daily basis and kept for 14 days. In order to get a restore to happen you need to add a service request from your Office 365 tennant admin center (support link in the left navigation).
Unfortunately they can only restore on site collection basis, which is quite big. If you lose a list or a document library, the only option you have is to restore the entire site collection.
However, there are options to use third party tools to make granular backup and restore if you like. Some of my customers prefer to have this setup to have the extra security since the cloud is the scary-out-of-control-cloud :-)
A week ago your link was referenced by Microsoft Officials on the O365 community, which makes it kind of offical.