OK... I've finally gotten around to looking at the downloads module. Since we moved to the new forums, and I broke the connection with the postnuke registration system (for the main site), which I'm still glad we did it.... anonymous users couldn't upload files to the downloads area.
Now anyone can upload files to the downloads area! The files still require validation from an admin, so please don't complain if you don't see your file in the downloads area immediately.
For the time being, files larger than 1mb can't be uploaded (even though the downloads module states that up to 10mb can be uploaded). I think this is a php issue, and I'm looking into it. But at least people can upload IPKs all you want and post them to the ZSI.