I and many others use Google Calendar to book our appointments, organize and join meetings, and otherwise block out our time. I really like Google calendar for all of those reasons and more.
And I, like many others, also suffer from "urgency addiction" -- constantly checking email for fires to put out -- as well letting interruptions like IM conversations break us out of the "flow." Interruptions like incessant new mail notifications and IM chat requests are productivity killers.
What we need is the ability to block out quiet times within Google Calendar to work on project uninterrupted -- in "Do Not Disturb" mode -- and for Gmail and Google Talk to automatically sense this status and then stop notifying you of incoming mail and put you in "Do Not Disturb" status in Google Talk for the blocked-out time. This would save us the step of always having to remember to sign out of Gmail and changing our Google Talk status to DND.