I would also invite people who read this thread to examine the "ArcGIS Desktop - General" forum. In there you will find "stuff" which should be in Arcobjects, Mapping, spatial analyst, and a whole whack of "geoprocessing" questions. For the most part, I suspect that people put their question in the forum that they think will get the most traffic. By suggesting/indicating via popup etc, what is appropriate material for a forum, then perhaps we could dispense with "General" altogether and put an "Other" category way at the bottom of the list perhaps enticing individuals to place their posts in a forum that is appropriate. Further subdivision...based upon what is in the "General" forum...won't make matters easier.
So...Geoprocessing should be described (I suspect there a lot of people who don't have a definition, and I suspect people's definitions would differ). I suggest that this would include MB, Python and Arctoolbox (we will leave the ArcObjects people along) and the term relating to calculating, working with geometry and the like. There is going to be no perfect answer, but tags etc would go a long way, in this way, I could simply click on my preferred tag cloud and get all threads for my interest regardless where they were placed. Special interest forums for the extensions could then remain where they were and there will undoubtedly be overlap between geoprocessing and their parent forum. That's it for me on this topic...keep it coming