As long as you actually enter all calendar data on Google Calendar, this is a top-notch solution, thanks to Google's support for ICS. My iCal, Outlook, my Verizon phone (using Verizon Wireless Access by Intellisync), and Lightning* all check the Google homebase for calendar updates. Depending on the service, the clients go haywire when I try to update calendars from the non-Google application, but it's pretty amazing that my calendar gets pushed to a bunch of devices, such that any one of them can be my calendar, to say nothing of any internet-enabled terminal. Gotta love 2008!
Now, if we could just stop raping the planet, technology would be so super-rad!