I think it would be a good idea to create a new area in the landing page of plugins and themes.
So next to Details, Review and Usage you could place a "Common Problems / Hot Tips" area or something like that where dev and staff can insert important pieces of info they have discovered through the process of working out solutions to member problems.
The forum should be the workspace and the "Hot Tips" area should be the reporting place where solutions to common problems are neatly organized (even if they refer back to the forum threads). It's essential to have something like this in between updates, especially since a single update doesn't solve everyone's issues.
Even if it doesn't cut down on redundancy of people asking the question, it will at least make it easier to point people to a place where the question has been answered.
+1 if you like this idea...
Thanks for listening,