John Ollila at Loyalty Lobby has the info via his latest US Airways Dividend Miles e-Statement:
Your final US Airways Dividend Miles e-Statement
Next month, we’ll reach the next milestone on our path to integration by bringing Dividend Miles into the American Airlines AAdvantage® program. We’ll transfer your mileage balance and elite-qualifying activity into your new (or existing) AAdvantage account.
Looks like it’ll be April for the official switchover from US Airways to American Airlines.