I got the following email from amazon in response to questions about the $50 dollar rebate:

Hello from Amazon.com

I do understand your concern regarding the $50 rebate for the Nokia N900.

I apologize for any inconvenience you've experienced.

I've researched for the rebate details and learned that it should be post marked by January 8, 2010.

However we expect this item to be available with us very soon. If by any chance we are unable to ship your order to meet the rebate dates, we will honor the $50 rebate to you.

I can assure you that we are working hard to obtain this item for you and we will ship it as soon as we are able to obtain it.

Once we receive stock of this item, we'll send you e-mail confirming the date, contents, and method of your shipment for your order.

I hope this solution works for you and we hope to see you again soon.

Please let us know if this e-mail resolved your question: