The Cardinals expected to release running back Adrian Peterson today, a source tells Adam Schefter of ESPN.com (on Twitter). By cutting Peterson now, the Cardinals will avoid paying a $750K bonus to the veteran, which was due on the third day of league year, Friday. 
We first heard back in February that the Cardinals were planning to release Peterson. However, Schefter hears that Peterson still could circle back to Arizona later, perhaps at a rate cheaper than his originally scheduled $2.881MM cap charge.
The Patriots, Seahawks, and Giants all expressed interest in Peterson before he signed with the Saints last year, so those are all teams to keep in mind as Peterson approaches free agency. Additionally, the Ravens discussed dealing for Peterson before the Saints traded him to Arizona last year.
Peterson, who turns 33 on March 21, managed 3.5 yards per carry on 129 attempts and scored two touchdowns for the Cardinals. He had his moments – like when he ran for 134 yards and two touchdowns in his Arizona debut – but he was among the least effective backs in the league overall. Football Outsiders ranked Peterson 46th among 47 tailbacks in both DYAR and DVOA, metrics which measure overall and per-play value.