Google Calendar has a new look that’s more consistent with other Google services like Google Docs or Gmail. Google says that the only functionality that has changed is that the Tasks link has been removed.
“Create event” is now a button, instead of a link. The calendar from the left sidebar has more visible arrows and it no longer has a blue background.
Here’s the old interface:
Update: The new interface is also available for Google Apps, but administrators need to enable pre-release features in the “domain settings”.