Silver Preferred can still reserve the exit row, so I don't think anything's changed:
Emergency Exit Row Seating
Only Dividend Miles Silver Preferred, Gold Preferred and Chairman's Preferred members may reserve seats in the emergency exit row in advance, provided they are aware at the time that the seat reserved is in an emergency exit row and they are willing and able to perform all related assistance functions.
http://www.travelagent.usairways.com...ents/seats.htm