We clearly need to do some promotion to get this site launched as Robert Cartaino has stated in this thread. During the build up to public beta there were at least four blog posts on the importance of the EE stack Overflow proposal and dozens of tweets daily. I think we should continue to do this sort of activity.
Additionally we need to be more proactive about getting existing members to participate. An additional option is to invite other well known developers who may not be involved in the private beta yet.
It would probably be a good idea to get Ryan Irelan or Kyle Cotter to post another news item about EE SO over at EE Insider.
Any other ideas for promotion?