Google Calendar and iPhone OS 3.0
Typically when someone schedules a meeting on UMcal my first instinct is to copy the information to a Google Calendar. I've got a few for work: one general work calendar, another specific to a topic I'm frequently involved in, and another more general University calendar marking holidays, starts and ends of semesters, and the like.
Among the new features in iPhone OS 3.0 is the ability to use CalDAV to sync calendars to your mobile device. Google Calendar supports CalDAV, and it's pretty easy to set up. Go to the Settings app, tap "Mail, Contacts, Calendars", "Add account...", "Other", and finally "Add CalDAV Account." Enter the following information:
Server: www.google.com
User Name: [Your user name]
Password: [Your password]
Description: GCal (or whatever you prefer)
iPhone will verify that you entered everything correctly and send you on your way. The only problem is that it doesn't sync all of the calendars on your account. Instead, it just gives you your default calendar. Fortunately, armed with a special token found on the calendar's setting page, you can add secondary calendars to your iPhone by creating additional accounts in the same manner as above and changing the "Account URL" in the advanced settings page.
First, you'll need to find the token for your calendar. Log into Google Calendar, click "Settings" at the top right, then the "Calendars" tab, open the detail page for the calendar you want to add, and then copy the "Calendar ID" listed near the bottom in the "Calendar Address" section. It'll look something like [random alpha-numeric characters]@group.calendar.google.com.
I haven't been able to find a way to get this token from the mobile version of Google Calendar, and I can't find a way to force the fully-featured version to show up in Safari on iPhone. I put the IDs in an e-mail and sent it to myself (which conveniently masquerades as a way to test cut and paste functionality).
Once you have the calendar ID you would like to add, create a new account, name it appropriately, and then edit the advanced settings for that account. The Account URL should be:
https://www.google.com:443/calendar/dav/[random characters]@group.calendar.google.com/user
Once that's in place, you should be set with multiple calendar goodness.