I was going to write a bit up about it but Manfred Moser from Sonatype has already put together a blog and video on it:
With the new Nexus 2.11.2 release we are supporting the authentication mechanism used for the Oracle Maven repository in both Nexus OSS and Nexus Pro. This allows you to proxy the repository in Nexus and makes the components discoverable via browsing the index as well as searching for components.
You will only need to set this up once in Nexus and all your projects. Developers and CI servers get access to the components and the need for any manual work disappears. On the Nexus side, the configuration changes can be done easily as part of your upgrade to the new release.
Check it out @ Using the Oracle Maven Repository with Nexus