How to Use Apple ICal to See Your Coworker's Google Calendar on Your Mac (OSX 10.7 Lion)
If your company is using Google Apps for mail and calendars, it's really easy to see your coworker's calendar in the web-based client. It also works for your friends if they happen to use Google Calendar.
But not everybody knows that it's also possible to see your friend or coworker's Google Calendar availability in Apple iCal. It's not quite as easy to find as the Google Calendar web version, but once it's set up you can just check a box to see their calendar in iCal too.
Before you start, visit your web-based Google calendar and add your contact's calendar by typing their name or email address in the "Other calendars" box as shown in the screenshot below. This authorizes your account to access their Google calendar.
First, Add Your Coworkers in Web-based Google Calendar
Once you've got your coworkers calendars loaded into your web-based Google calendar, you're ready to add them to iCal.
Note: these instructions are for Mac OSX Lion v10.7. In previous versions the iCal preference panel looks the same but you add your Google under the iCal preferences instead of the system preferences.
Now Connect Your Mac to Your Google Account (if you haven't already)
You may have already set up the calendar if you're using Apple Mail to access your Gmail. In OSX 10.7, the Mail, Contacts and Calendar settings have all been moved to the system preferences panel. You add your Google Calendar account the same way you add a mail account. Just choose the "Gmail" option and then be sure to check the box next to the "Calendar" option.
In Apple System Preferences, Add Gmail to "Mail, Contacts and Calendar"
In iCal, Add Your Calendar Contacts as "Delegates"
Once you've got your Google account connected to your Mac, open your iCal preferences and select your Google CalDAV account under the Accounts section. After selecting the Account on the left, click the "Delegates" tab of the preferences for that account. This should load up all of the calendars for the same contacts that you have access to in the web-based Google Calendar.
Select your friends or coworkers calendars to add to iCal
Now you should be all set up. Your coworker's calendars should now show up as options under the main "Calendar" button in the iCal interface. You can hide or show their calendars there.
(If anyone knows why two apparently duplicate checkboxes appear for each delegate, feel free to enlighten me. I'm assuming that perhaps a delegate could have more than one calendar, but none of my delegates ever have.)
Shared Calendars in Apple iCal
Bonus: Use iCal to Find an Available Meeting Time
Once you have your coworkers calendars in iCal, you can use those calendars to help find an time for a meeting when everyone is available. Again it's not quite as easy to find the iCal interface, but it's there.
Add Invitees to Your iCal Event
If you have access to that contact's calendar then you should see an option appear under the invitees panel lableled "Available Meeting Times".
When you click "Available Meeting Times" it opens up a new window were you can easily see times where all invitees are available. There's even a handy "Next Available Time" button to quickly take you to the first time that everyone is available. Neato, huh?