Official Gmail Blog: Tasks, now in Calendar too
As from title itself is enough to let you know that new feature that is added to google calender is tasks.
Now just as you add an event , you can add task to do to you google calender
Tasks ,you got to do will appear on your calendar. To create a task , click on space in monthly or day view view, select the "Task" option.
To add a due date to an existing task, right click within the task list, and then click on the calendar icon.
To mark a task completed , just click on the task checkbox.
To keep track of dates before they arrive, there is a notifier as new "Sort by due date" feature available in the Actions menu at the bottom in the task list.
While sorting by due date, you can reschedule a task by clicking on it in your list, then pressing control and the up or down arrow key.