A wiki page of the Road Map along with a rough timeline would be a good start. I also think that tying the Road Map to a timeline will cause people to more closely examine the time a particular feature might require. But like the Linux kernel release schedule, determining any kind of regular release schedule may prove to be quite difficult. But IMO it can't hurt to have goals.
Could use the Road Map feature of JIRA... though I think that works better with more frequent releases (so that the number of issues is less). I like how Atlassian uses their JIRA (and Confluence) to organize their releases. I would like to see G use something closer to their approach.
--jason
