The process is already described here:
http://www.ubuntugeek.com/how-to-sync-google-and-evolution-calendars-in-ubuntu.html.
It's not much of a post, but it may be of help to someone who tried the Google option when setting up the calendar sync in Evolution and found it less than satisfactory.
Edit 16/12/2011:
Recently (last two days, version 3.0.3-3) been getting error messages in evolution when trying to connect to my google calendar. While using the method described above for a while I switched to using 'google' instead of 'caldav' as the calendar type at some point. Well, it doesn't work anymore.
Here's how to use google calendar in Evolution:
New -> Calendar
Type -- CalDav
URL: caldav://www.google.com/calendar/dav/myemail%40gmail.com/events/
Use SSL: yes
User name: myemail@gmail.com
User email: myemail@gmail.com
Then clock 'Browse server for calendar and select the
+ /calendar/dav/myemail%40gmail.com/
- myemail@gmail.com
Whether you want to copy content offline or use it as default calendar is a personal choice.
Edit: 16/12/2011 -- 2 hours later
Well, it's not working anymore. Same TLS handshake BS as before.
"Error loading calendar
Cannot open calendar: Unexpected HTTP status code 6 returned (Peer failed to perform TLS handshake)"
What I can't understand is why there is no good description of this problem on the web, given that Evolution is the default email and calendar client for gnome. I don't like thunderbird/icedove+sunbird/iceowl much, but things seem to work better in general there.