We used to have the Rails forum broken down into two forums: Beginning and Advanced ... but unfortunately, those were too subjective and we found people posting the same sort of things in each forum (i.e., what's advanced to someone using RoR for 3 months might feel like a beginner topic to someone using RoR for 2 years). So we merged everything into one forum, which admittedly makes the forum move very fast.
The best answer I can give for now, is to attempt to use the additional category forums we have now as much as possible where appropriate. (That is, anything about databases, for example, put in the databases forum even if it has to do with rails+databases.) I think if we can get more people thinking about where to post, and taking advantage of the forum structure, instead of just immediately posting in Rails, then we'll alleviate the problem a little.
If you have any more suggestions, we're certainly all ears.