I happen to have a great exposure working with the Content Deployment in an authoring and production topology:
Authoring and production farm
The two-farm topology is a standard Internet site topology, and it is typical of topologies that are used to publish an Internet site. It includes two server farms: one to host the authoring site collection along with other sites that are used by the authoring team, and the other to host the production site collection. Users of the production server farm belong to a separate Active Directory® domain, and some production farm users might be anonymous.
Extranet sites with read-only access.
Authoring, staging, and production farm
A three-stage topology includes an authoring farm, a staging farm, and a production farm. The staging farm is used to test or review the content, in addition to custom Web Parts or code, before it is published to the production farm. The site collections for authoring and staging can be located within the same farm.
Environments where a multistage approval process is a business requirement.
Validating content in an environment that more closely reflects the production environment before deploying it to production.
Testing the content with custom Web Parts and code before moving it to the production farm.
Single publishing farm
· Intranet environments.
· External environments in which staging verification is not a business requirement.
· Segregating security settings and authentication between two locations, when only one farm is available or necessary.
I happened to have worked with content deployment topologies including two or more server farms in both MOSS 2007 and SP2010, to separate the authoring environment from the production environment. Typically, the destination server farm (the "production" farm) has tightened security to minimize the actions that can be done in the production environment. It is not expected that authoring will be done on the production server, because changes to content on the production server might be overwritten by a content deployment job. The OOTB content deployment usually set-up to run after every 15 minutes. On the other hand, a custom code approach can be used to set up the process with some detailed settings.
CD in MOSS 2007 has a lot of problems while pushing down the content during creating/editing/deleting. However, SharePoint 2010 is shipped with some more features provided in Content deployment and migration API.