Mtux says Mizuho Bank's automated wire transfer API is broken right now. Wires can only be sent out manually by Mizuho. Gox is opening accounts at other banks, which should drastically improve USD withdrawal times and bypass the technical problems at Mizuho. This process should take around 2 weeks.
LOL W(hy)TF didn't Mt. Gox just put THAT info in the press release? They seem to love crafting press releases designed to maximize panic.