Starting tonight (January 8), frequent fliers who are both AAdvantage members (AA) and Dividend Miles members (USAir) will be able to start the process of eventually merging their accounts into one. The step now is to match up the two accounts so that when the merger takes place "in the second quarter" it will go smoothly (no questions about whether John Quincy Traveler is the same person as John Q Traveler Jr). MORE from ThePointsGuy website.
ADDED INFO: As PortMoresby pointed out (below) it's very simple; in fact so simple that you only have to do it on ONE of the two websites, rather than entering info on both. So far, the smoothest of the three big mergers.