I bought my N900 on Newegg a week before Christmas (not a pre-order), and did receive my rebate card but only after first receiving a letter telling me I failed to include my Ovi username (which I, of course, did include in the original form).

I called the number on the letter, they asked for a case number or something like that which was printed on the form. She put me on hold for about 2 minutes, came back and said everything is taken care of and I'll receive the card in about a month. And I did. And I felt lucky every time I opened my wallet and saw the Nokia card...