We're sure that MetroPCS and T-Mobile USA executives were on pins and needles wondering whether or not their proposed merger would clear all the regulatory hurdles. While they're not officially free and clear, the Department of Justice has given a strong hint that the carrier union will go through. The government branch just let the mandatory waiting period expire without raising any objections; if it had thought there were serious antitrust issues, it would have piped up by now. Before anyone pops the champagne corks, though, there's still a number of formalities -- the Committee on Foreign Investment, the FCC and the companies' shareholders still need to sign off on the deal, which could take weeks or longer. Considering the troubles T-Mobile had the last time it tried a merger, though, waiting will seem like a walk in the park.