SharePoint 2010 offers new metadata features including tags, social bookmarks, and content ratings. These new types of metadata are stored in the service applications that reside outside of the content database. For example, enterprise managed tags reside in the Managed Metadata Service application. You should make sure to back up all of your service applications to ensure that all metadata is protected.
Any metadata that is stored outside of the content database cannot be restored using Granular Recovery Technology (GRT). You can, however, use GRT to restore SharePoint data with metadata attached to it. As long as the metadata resides in the same service application, SharePoint maintains the link between the data and the metadata.