Sonatype Nexus 1.0.0-beta-2 has now been released. A list of the changes can be found here. If you are upgrading from beta-1, be sure to see the new upgrade section in the Nexus chapter of our Maven book.
Nexus is a Maven repository manager that is able to host your internal repositories, proxy downloads from external repositories, generate indexes consumable by M2eclipse, and if you ask nicely, it will even do your dishes!