It's well known that ArcGIS only takes advantage of multiple processing threads to allow a single geoprossesing task to occur in the background while still interacting with the GUI. Any further processing is placed in a queue. A signifficant improvement on this (other than making the whole program multi-thread capable) would be to make batch geoprocessing tasks utilise more than the single thread currently used. If I run a batch of 4 Clip processes, there's probably no reason that at least two can't be run on parallel threads on a modern workstation (even my 3 year old workstation has 4 cores).
This could also provide some relief for the fact that ArcGIS for Desktop is 32-Bit and hence somewhat hamstrung by limited memory access - processing large datasets which run out of memory could be done by breaking them down into tiles and running the required geoprocess on the tiles in parallel.
