Well, it's like a very inconvenient coupon. The idea, as far as I can tell, is that they can offer a larger discount to some people, because many customers won't bother filling out an obnoxious form by hand, snail mailing it, and waiting 6-8 weeks for a check (ahem, "cheque"). Less reputable rebate processors also have a habit of "misplacing" your rebate check, hoping you've forgetten about it. T-Mobile did that to me last year.
Any new MBP would not be available on Amazon for at least a couple of weeks after release. The only glimmer of hope here is that the rebate period falls one week short of the usual one-month Amazon rebate period for the MBP. However, the current MBA rebate also ends on 3/11, so go figure.
I still find it amazing that with the hundreds of people (suppliers, manufacturers, vendors, etc.) involved in MBP production that not one credible rumor has floated to the surface. Apple sure knows how to keep everybody working in their little silos.