The collection module tracks the relationship between revisions of content.
Example collection: Fall 2013.
This collection would contain all of the revisions that are associated to the Fall 2013 collection. Then you can perform operations on these collections in bulk.
There is built in integration to the sps module to allow the site to be previewed with a collection active.
Please note this is still under heavy development and will most likely be very large changes including the API.