Actually, I keep getting an error message, even when I am the only one to received the invitation.
[code] There was a problem receiving this invitation.
Someone invited you to an event using an email address that isn't on your "me" card in Address Book. Find your email address in the following list and add it to your card in Address Book.
[/code]

But I am listed in my address book, with the right address. Any clue?

I am experiencing the same problem and thinking it might be a caps issue, I tried all kinds of iterations of my email username to try to capture the address the invite thinks it was sent to -- no good. It still doesn't work.

I had the same problem, it turned out that my palm pilot had put my phone number where my e-mail address was and vice-versa.