Google Calendar Starts Testing "Sneak Preview"
Once you’ve activated Sneak Preview (assuming you have access to it), whenever you create a new event you’ll see a new viewing mode that displays a calendar alongside your event details. This calendar will show the schedules of each of the people you’ve invited to the event (provided you’re a friend or coworker with access to that information), and the proposed time for your event will appear as a semi-transparent blue box so you can quickly see where you might have conflicts. You can click each guest’s name to show/hide them on the calendar if some are more important than others.