You can copy/paste in any text entry field. Entire appointments? I don't think so. But you can repeat apointments, or edit it to move to a different day.
You might look at other calendar / time management apps, though, and see if there are any that suits you better. That's the beauty of having an app store, after all!
Thanks, its probably something that was simply overlooked. I don't use a Mac, but does iCal let you do it. When I was using Windows Mobile you could do that. If its something that might be added that would be cool.