Jay Manley offers a Fun Milestone: GP 2013 Beta Code – 500 unique downloads. Frankly I would have expected more, however, we downloaded a copy to the office network and made it available to our consultants from there. It reduces the load on the internet pipes that way. I wouldn’t be surprised to hear that other partners did the same thing.
Fun Milestone: GP 2013 Beta Code – Inside Microsoft Dynamics GP – Site Home – MSDN Blogs
Development & IntegrationMicrosoft & the GP EcosystemGP 2013
Archived post from 2012. Dynamics GP and the links it points to have changed since; check current documentation before relying on version-specific steps.