Originally Posted by dstan

• What are Preferred seats?

Preferred seats (previously Express seats) are at or near the front of the coach cabin, including bulkhead rows, and are available for purchase up to 24 hours prior to departure. Pricing starts at $4 per flight one-way and is based on flight distance. As of August 25, 2011, Preferred seats are available free of charge to AAdvantage and oneworld elite members, AAirpass members, full fare/AAnytime award passengers (Y, B), active duty U.S. military, and their traveling companions on the same reservation, beginning 24 hours prior to departure. Preferred seats cannot be reserved earlier in advance and are available for purchase through AA.com, phone, or airport self-service kiosks between 24 hours and 50 minutes prior to departure, even after previously checking in online.

Prior to August 25, 2011, the previous Express Seat product also included Group 1 boarding, but was not available to those traveling on AAdvantage Award tickets. AAdvantage elites and full fare passengers were still charged for Expressed seats, unless selecting seats with an airport agent.

AA.com: Seating Options | FAQ
FT: Express Seats - Paid premium seating in economy
FT: Express Seats rebranded as Preferred Seats (Aug 25, 2011)