At first, I thought gmail took away my last invite (I am saving it for a special someone). But then Marcia, in this thread at Search Engine Watch pointed out that the invites were still there, but just available as a link within the email.
GmailRep at Search Engine Watch then added, "Now the invite a friend link is on the left side, underneath your labels in blue. This link will also appear in red at the bottom of a message from a non-Gmail address next to the reply links."
