Word from THR is that Marvel's Agents of SHIELD is getting an appearance by Bobbi Morse aka Mockingbird and it will be played by Friday Night Light's Adrianne Palicki.
The character will be making her debut in the fifth episode of the season and may return in the future… but she may not be an ally for Agent Coulson and his team.
Palicki of course is not new to this type of genre having played Wonder Woman in the ill-fated pilot by David E. Kelly. She also played Lady Jaye in G.I. Joe: Retaliation.
The character was teased in this footage from Comic Con starring Patton Oswalt as the Koenigs.