I've redeemed AMEX MR points to US DM before, and like other transfers I've done from AMEX to airlines it takes a few days, pretty quick really, never more than three days or so. So I got this offer yesterday:

http://www.flyertalk.com/forum/Forum69/HTML/000911.html

Register and make a redemption online and earn 1,000 bonus AMEX MR points. Even though I've already registered and redeemed, I'm going to see if I can earn it by following the instructions, so I logged in did it and transfered 1,000 points to US (they'll be free if it works, if not, no big deal).

The very next thing I do is open Miletracker ( http://www.miletracker.com ) to see what points posted in the last day to my various accounts. It loads and checks and says I have 1,000 more US miles than yesterday. So I click Launch to see where those points came from. I almost crapped my pants, they were the transfer I had just done one minute earlier on the AMEX website! WOW!