Google Blog posted an article about Google Calendar this morning mentioning it is available in more languages now. That's cool, but the update is a bit larger than the article lets on.
People outside the United States can now use SMS notification for their calendar events now too. In settings, choose your country and carrier for your mobile phone -- unfortunately the one I tried (SaskTel in Canada) doesn't appear to be functioning properly yet.
These are the only major changes after looking at the service briefly, but I am doing more digging to see if anything else has changed. If I find anything, you will be the first to know.