It may be that calendar was not in a usable state in 4.5, so an upgrade script might not be absolutely needed if no-one is using a 4.5 version of calendar. I don't know though, so I left it alone 😊
Calendar doesn't seem to be working in 4.5. I just came back into the OpenACS "fold" after a long hiatus (woohoo!), and finished setting up a 4.5 server (release tarball) this weekend for my home site. I was intending to play with calendar; it installs, but it breaks when attempting to add an event. So I'm guessing no one is using it. I may go in and fix some of the bugs for my site, but I don't think it's being used in general.
