It looked like it was more of a deflection than an own goal, but I am not sure what Atlanta player it went off of.
Bobo was the player who deflected the shot, by stupidly sticking his foot out (and as a 'keeper, myself, I hope McIntosh ripped him a new one). Originally the goal was credited to Leighton O'Brien, but the scorekeeper must have felt, after reviewing it, that it would not have been on frame if it hadn't been deflected. Having watched it several times on Comcast On Demand, I think Leighton got robbed, because it looked like it would've been on frame regardless of the deflection.