This was fine, and Tiny was able to work around it, changing the channels through which oQueue operates. Then a change was introduced to remove notes from battle.net invitations -- an attempt to remove a way for spammers to advertise their gold and other services. However, this completely broke oQueue's capacity to let people join groups.
Fortunately, Tiny tells me, a hotfix is in the works to repair this latest issue. The hotfix also makes another API change which Tiny will release a new version to work around. This hotfix was scheduled for this week, so hopefully our favorite in-game group-finder will be up and running again soon. Keep an eye on oQueue's host site for the latest updates.
Update: The hotfix is now live and