To make changes to the calendar, press the Google Calendar button at the bottom right of the calendar above and sign in as:

jnullspace@gmail.com

You can subscribe to these calendars in iCal by using the iCal menu item Calendar→Subscribe and entering the following:

GRU Calendar:

http://www.google.com/calendar/ical/jnullspace@gmail.com/public/basic.ics

CBS Seminar:

http://www.google.com/calendar/ical/bm9ioeurp9p3mii15hn5spsrhk%40group.calendar.google.com/public/basic.ics

DJC:

http://www.google.com/calendar/ical/4vjop8gu2sil0es4rtdvvouji8%40group.calendar.google.com/public/basic.ics

This will give you read-only access to the calendars in iCal.