discovered the new sort features:
if you highlight a track, do a "get info" and then click on "Sorting" you will find that you now have options to enter various common tags however you choose them to be.
You can then sort by your new tags.
I suppose a simple example is that you could create a subcategory of all your Bob Dylan songs that could be live recordings, by calling them "Dylan live" in the "sort artist" option.
There is a discussion of this
HEREDoug's Applescripts for iTunes already has a script for this fieature. This script will allow you to batch-set the new sorting tags ("Sort Name", "Sort Artist", "Sort Album Artist", "Sort Album", "Sort Composer", "Sort Show") of the selected tracks, rather than manually doing so one track at a time. ยป