Reposado eliminates the need for Mac OS X Server (and Apple hardware) to host an internal Apple Software Update service. Reposado, a set of tools written in Python, replicates Software Update catalogs and updates. You can then use any available web server to serve these to your clients.
Additionally, Reposado allows you to easily implement an unstable/testing/release workflow, where you release updates only to a small set of machines for testing before releasing the updates to the rest of your managed machines.
Finally, Reposado allows you to continue offering “deprecated” updates. When Apple releases a new version of iTunes or Safari or a new Snow Leopard update, previous updates are no longer available from Apple’s update servers. But with Reposado, you can continue to offer these “deprecated” updates to your machines until you’ve tested the new versions.