This isn't official, as I haven't found it anywhere else yet, but Andy Strickland of HockeyBuzz.com reports:
Chicago signs former Blues D-man Matt Walker to a 1 yr. deal.
From looking at Walker's stats and the scouting on him, it looks like Walker would bring some toughness and depth to the blue-line. Not a tremendous addition, but he's got good size and would give us a physical player. Not a bad signing if it is true.