To keep up with new Google properties like gCalendar, Google has ditched the popular Gmail Notifier for a revamped application aptly dubbed Google Notifier. The new Mac application adds a calendar icon to your menubar (you can hide it in preferences) and a Mail.appetizer-esque notification system. When you get a new email or calendar reminder a transparent window pops above your top right screen as a friendly notification.
Other additions include two new sounds, Google Beep 1 and 2, yet the notifier application can still only handle one Google account at a time; no fancy switching or simultaneously using multiple accounts, yet.