I can remember when these various calendar apps first came out and each was what the cognoscenti like to call a "walled garden": if you didn't use that app, you were out of luck. Not so good if you're part of a team and don't feel like imposing tools upon colleagues (or family members). Fortunately things have improved significantly since then and there's a lot of interconnectedness between the different applications, and iCal can handle a number of different calendar formats too.

As far as I can tell, however, if you subscribe to an external calendar on iCal, that doesn't translate into it being disseminated across your Mobile Me account, so you might have to move some appointments from one calendar to another if you want to edit them or see them on your remote device.

In terms of just seeing more than one calendar, however, it's pretty easy. To do this you'll want to be logged in to your Google Calendar account and have already accepted the sharing invitations from your colleagues so that their calendars also show up. You'll also want iCal running.

Now, step one, go to Google Calendar and pop up the contextual menu associated with your colleagues calendar:

Choose "Calendar Settings" and make sure you're on the "Calendar Details" tab. Now scroll down to the bottom. You'll see:

On the "Private Address" Option-click on the "iCal" button. Now you'll see this:

Choose "Copy Link" and you're done with Google Calendar.

Flipping to Apple iCal, choose Calendar --> Subscribe... and you'll see this little window:

If you're guessing that you paste the URL you've just copied from Google Calendar, you're right! Do so, click "Subscribe", and you'll shortly see:

Before you leave this window, you'll definitely want to change the auto-refresh setting so that if they update their calendar, your view updates too (in fact, it's odd that the default is to never update!) I suggest that daily is sufficient unless they're constantly changing their schedule, in which case you might consider hourly, or even more frequent.

Get everything configured as you like, then click on "Okay" and you're done! The calendar now shows up on iCal on the left under "Subscriptions".

Hope that gets you going with Google Calendar / iCal interaction!