After some research I found the details of each of the Cardinals draft picks that have signed. Each pick agreed to three year deals for the minimum amount per season: $295,000 (2008), $385,000 (2009) $470,000 (2010). I also found that Early Doucet got a $550,000 signing bonus but I can't find if any of of the other picks received a bonus upon signing.
There's also some promising note that the Redskins singed one of their second round picks, Malcolm Kelly. The significance of his signing is that he was drafted on spot behind the Cardinals second round pick, Calais Campbell. The Cardinals will likely use Kelly's contract as a starting point in the negotiations with Campbell. Kelly's contract is a four year deal for 3.36 million and includes $1.655 million in guarantees. The Cardinals have just over a week to finalize deals with both Campbell and Dominique Rodgers-Cromartie.