One thing that we've been asked recently is whether we'll enable groups and group contributed outlines. We're working on enabling groups with permissions and collaborative workspaces but we're still a bit off from there yet. In the interim, though, I though I'd post a quick little workflow that might enable something similar.
One possibility is to register an account with a "group" name. Give all the people you want to have access to the group space the username and password. Then anyone who points to http://grazr.com/opml/[GROUPNAME] will get an inclusive OPML file of the latest files uploaded to that account. If widgets are generated from that file then anyone can have an up to date published version of the group's outlines. When our bookmarking system comes online this will be even more useful as accounts will be able to be cross included into the group outline using the "include" mechanism.
It's not a perfect solution but it should allow a minimum level of collaboration. We are working on it though.