Created originally by Greg Dunlap at Palantir.net for Foreign Affairs magazine, this module copies Drupal objects between servers. Since Drupal's data is contained within a database and there was no guarantee that table information would be identical from one database to another, Dunlap designed a system that maps Universally Unique Identifiers (UUIDs) to Drupal serial IDs.
"This gives every Drupal object (node, taxonomy term, user, etc.) a unique identifier that can be used no matter where the node resides, but leaves Drupal's primary key management unchanged," says Dunlap. "When an object is deployed, the remote server is queried to see if an object with that UUID already exists or need to be updated. If so, it gets pushed," using the Services module.
From there, Dunlap also created both a system that manages object interdependencies to ensure that objects that depend on one another are all pushed together and an API for building custom deployment scripts.
For more, watch Dunlap's screencast demonstrating Deploy in action. For information on other options, see our earlier coverage on multi-site management.
Greg Dunlap's video on the Drupal Deploy module in action.