Over the last few weeks many people have been reporting unwanted Calendar invites, usually looking like junk email with a sales pitch and links. It is difficult to get rid of these invites without notifying the sender that you either declined or accepted it. But there is a method to quietly delete the invite. A better solution is to switch to email notifications of Calendar invites until Apple fixes the problem.
Data Detectors allow you to turn addresses, phone numbers and dates in mail messages into Address Book contacts and iCal events. You can also turn selected text into to-do items or stickies.