Not that this is really new information, but it looks like only two of the posts actually deal with the "challenge" qualifications.
I qualified as Silver Preferred in November 2001 under a challenge program (fly something like 6250 miles). In early December, I received my welcome package that included 2 DMUPSYS, 2 DMUP01, Club coupon, and a membership card with an expiration date of 2/28/03.
Today I received my new preferred packaged and the only thing in it was a Club coupon (become a member and get 3 free months).