Answer: none, AFAIK. You might argue that you can just add user manually or share calendar by XML, iCal, or even HTML link. That’s just like the way regular Google account can do. What is good about Google apps then?

1. You can set your accout’s calendar to share with everyone in the organization. That would work too and it’s pretty easy to for others to add since that calendar has a name as your email account. But I bet you wouldn’t want to share what is yours to others, would you?

2. Add new calendar, then set share to everyone and share the link. It’s a bit harder then the first option, but that works.

What is a drawback of these two options? It’s pain in the ass if you want everyone that shares the calendar to add/edit too. You have to add each of the manually individually. In short, if you want then to just see, either of these is OK, but not for collaborate.

How? You think Google leave this out really, huh? No, they have a way for that.

[yourdomainname]_@domain.calendar.google.com

That’s the only one calendar ID that anybody can add, and everyone has full permissions! Anyone in the Google Apps can just put this ID to “add a coworker’s calendar” then simply “enter.” It will go to your calendar easily. For the sake of privacy? people outside your Google apps won’t be able to even see.

I would love to have more choices, but so far I have yet to find other ways. If you know any other, please share =)

Added [the day later]

The easier way, and probably better way, is using group. You have to create group then add users or add all. When you want to share, just add team email to the calendar. Google will send out invitation email to anyone in the group automatically. The calendar ID will be like [domain]_[calendar.ID]@group.domain.calendar.google.com and this works similar to domain.calendar.google.com—outsider can’t access in any way.

Popularity: 9% [?]