I got invited to try out a new feature in Google Calendar called Sneak Preview that allows you to simultaneously preview your friend's calendars while creating an event. Currently in Labs, the "Free or busy" gadget already allows you to check the present availability of your friends but when scheduling an event, you would still need to go to a future date, cross check your friend's calendar to make sure that all of your guests are free during a particular time before creating the event.
With Sneak Preview, you would be able to preview your friend's calendar on a new mini-calendar in the Create Event screen. This makes scheduling events much easier by allowing you to see when people are free and if the proposed time would conflict with existing events. Here's a screenshot of Sneak Preview in action:
This feature, however, might not be as useful to users who own several personal calenders (e.g. one for work and one for personal) as it currently only shows your default calendar.
If you're invited to test the new feature, you should see a link in your Create Event page:
Do you think this feature would make creating events easier?