This has been hashed out quite a bit already. We have yet to find anyone that had problems with the automated system. Though with a few hundred thousand to millions of fliers doing these over the past few years, there must be some.
Delta indicated that it would take some time for them to post. It is not the same as your normal miles.
Check these postings:
http://www.flyertalk.com/forum/Forum21/HTML/003114.html
http://www.flyertalk.com/forum/Forum21/HTML/003088.html
this one has these links at the bottom:
Double BASE mile offer,
Posting of Medallion Double Miles - answer from Delta,
Double Miles Information - New Thread , and Double Miles - Other Airlines follow suit?