[Weiner] told EW exclusively that his new deal has yet to be finalised but he’s “not looking for a new job.” The show’s future is vague because [US cable network] AMC is still negotiating with both Weiner and [production company] Lionsgate, which produces the hit drama starring Jon Hamm.Hopefully Virgin will have Sky Atlantic HD by the time season five finally airs. But "we have not started writing"? Sounds like it may be quite a long wait.
“I think all of AMC’s decisions about their scheduling and so forth have nothing to do with me, and I don’t have a deal yet,” Weiner told EW, “I have every intention of making the show when they decide to work out their business with Lionsgate. But the truth is I don’t even know what their plans are. We have not started writing. I am not back at work. My contract expired. [...] It would be heartbreaking for me if they don’t work it out, horrifying really. It would be a shame for fans to never get to see what great stuff we have planned for Don and company.”
UPDATE: Meanwhile, those nice BBC schedulers have season four repeating from Monday, Jan 31st at 11.20pm each night (Mon - Thurs) on BBC2. No showings on BBC HD that I've found though.