This is finally working for me in Intrepid Ibex (8.10). I am able to sync my desktop calendar with the google calendar without noticing that Evolution is involved. My primary goal was to get calendar events to show up in the clock/calendar dropdown in the top right corner (by default). To do this is actually pretty simple. In the settings for your Google calendar, copy the private ics link. Paste the link into the address bar and change the http(s) to webcal. Hit enter and it should prompt you to open it using evolution-webcal. Let it do that, answer the questions it asks and all should be good in the world.