Currently, it seems that the only way to get the 'change_set' (or deltas) between two versions is to use the ArcMap GUI interface to that or via custom ArcObjects coding. It would be really nice if there were an api exposed to ArcPy for this. Something along the lines of arcpy.getChangeSet( parentVersion, childVersion, [optional table(s) list]). This might return an array (or structure of some kind) containing the changes between the versions. This could be useful in reporting changes, monitoring, etc. As well as determining deltas that might need to be sync'd with other data repositories, etc.