Previously, it was possible to delete an appointment without sending a
notificaiton resulting in you showing "attending" on other people's pcs,
while your calendar shows that time as free. It is no longer possible; the
deletion now removes you as an antendee in the meeting. What was even worse
was an organizer changing the time of deleting it without sending an update!
If you're not using exchange, I think they should still let you do this, but
that's my opinion.
Source:
http://office.microsoft.com/en-us/outlook/HA100926831033.aspx?pid=CH101535021033
Meeting updates A person who creates a meeting can no longer change the
time or location of the meeting without sending an update. Similarly, an
organizer can no longer cancel a meeting or send a cancellation request
without sending an update. However, a meeting organizer can still change the
body, subject line, and reminder time without sending an update.