This would be beyond useful.
We run a good number of sites on our MSM. Most of the sites are departments within my institution. The rest of the sites are what I refer to as “centralized services.”
For now we have News set up as a site and the Calendar set up as a site. Both of these sites disseminate news and events respectively based on the categories an individual story or event is tagged with.
It would be great if those two sites could share one category group (a list of all the departments) and, more importantly, the ID numbers.