Gulp. FCC chairman Kevin Martin is prepping for a big ol' congressional probe this morning. Martin received a letter today warning that he is being investigated for, "management practices that may adversely affect the Commission's ability to both discharge effectively its statutory duties and to guard against waste, fraud, and abuse." Martin, you'll recall, was recently accused of being in Verizon's back pocket during its attempt to revise the 700MHz open-access rule. The investigation is prompted by allegations made by "credible" FCC employees, both current and former, so far reaching -- including its handling of Comcast and the so-called, 70-percent ruling -- that Ars Technica expects it to turn the "FCC upside down." Martin has two weeks to deliver "a truckload" of records to Congress before this revolution gets televised.