I found DPR's altoid account, but I don't see the silk road advert post dated January 29th, 2011. The earliest post is from February 25th, 2011, and is about running bitcoind on Debian...
https://bitcointalk.org/index.php?action=profile;u=3905;sa=showPosts;start=40I suspect DPR deleted the post (wouldn't you?) and the FBI found it by requesting logs from bitcointalk admins.
Theymos, can you confirm?
Even if he could confirm, he is probably under restriction not to.