Here's a video that discusses the benefits of Hosted Repositories and how Nexus Professional's Staging Suite introduces the concept of the managed release. With the Staging Suite, you can configure filters that will automatically intercept a deployment to a Hosted Repository. Once the staging suite intercepts these artifacts, they will be placed in a temporary staging repository and a QA or administrative user will be sent a notification that a staged release is ready for approval or disposal. This mechanism allows a QA group to certify a release, once a release has been certified it can be promoted, and the contents of the temporary staging repository will be published to the hosted repository.
Nexus Professional: What is Staging? from Sonatype on Vimeo.