Google Sync Multiple Calendars on Your iPhone (version 3.0 or later)
Yes, you see it correctly.
Google now allows you to sync multiple calendars to your iPhone or iPod Touch (version 3.0 or later) by creating a CalDAV account.
Not only is it cool because you can have multiple calendars synced, but they're color coded like unto what you see when looking at the calendar in Google's interface through your web browser!
In the picture above, the blue dot represents entries from my scouts calendar; the red is from my personal one.
Don't delay! Go follow the detailed instructions on how to set your iPhone or Touch to sync multiple calendars from Google's help pages...