Keith over at Northlight Images has new information about the since long awaited EF 200-400mm f/4L IS Extender 1.4x lens. They were:
[...] told (thanks) that the formal announcement of avallability for the 200-400 will run alongside a camera announcement, most likely the 7D mk2, in time for shipping of a few units in the Autumn. There are quite a lot of test units in circulation and despite there being no official price, a lot of lenses have been pre-ordered. If (and at £10k that’s still a big if) the preorders are taken up, supplies will be very thin on the ground until well into 2014.