This was a great thread... I called up the AMEX Platinum line and just told them I heard about the promotion regarding a free AMEX AeroPlan Plat card for current holders.

I got transferred immediately to the Aeroplan department. Surprisingly, the agent tried to talk me out of it because as she stated, I earn 1.5 points on my current Plat but only 1.25 with the AeroPlan one. Once I told her I really only wanted it for MLL access, she said no problem and fixed it up for me.

I received the entire package about a week later. I was reading through the fineprint during some commericals and there is a line in there that said that the annual fee of $399 was waived for AMEX Plat cardholders provided that they continue to hold the AMEX Plat card as well. If that is cancelled, the annual fee kicks in immediately for the AMEX Aeroplan one. Rather nice of them to actually put it in writing

Cheers, and thanks for the tip folks.