Jeff Potts has an update to his cogent post on Alfresco's insularity. According to Jeff, John Newton and Kevin Cochrane promised to create a system that would allow non-Alfresco employees to contribute to the Alfresco code base. The changes are expected when Alfresco releases 3.0 of the Enterprise Edition. At this time, the Community Edition (which Alfresco treats as a "lab" for introducing new, unsupported features) may start to accept contributions from non-Alfrescans. The prospect of committer status is unsure.
What makes this a big deal is that Alfresco has always hobbled the Community Edition to drive sales to the Enterprise Edition. First, they stripped down the Community Edition. For a while they made it badgeware. Most recently, Alfresco's policy has been to forbid integration partners from helping Community Edition users. Because Alfresco doesn't fix the bugs in the Community Edition and Alfresco partners will not help you implement and maintain it, the Community Edition is too risky to use for most companies to consider.
Opening up Alfresco Community Edition would allow a community to form around the project that may make it more viable to use in the same way that companies use Fedora Core as a lower cost alternative to Red Hat Linux.
In the open source content management world, Magnolia is a good example of a commercial open source company that has non-employee committers on their Community Edition. The Magnolia Community Edition serves as the core on which the Enterprise Edition is built. In order to get support, you need to buy the Enterprise Edition whether or not you intend to use its value added features (Sitedesigner, clustering, etc.). Other commercial open source projects like Hippo and Daisy have one open source licensed product and make all their revenue on support and training contracts which are entirely optional for companies that adopt their software. However, Magnolia, Hippo and Daisy are small and not so heavily venture funded, so they have less pressure to convert adopters into paying customers.