Canon has released information today on when they now expect the previously announced EF lenses to be released.

Canon EF 8-15mm f/4L Fisheye USM lens is scheduled to be available in late July 2011
Canon EF 300mm f/2.8L IS II USM lens is scheduled to be available in late August 2011
Canon EF 400mm f/2.8L IS II USM lens is scheduled to be available in late August 2011
Canon EF 500mm F4L IS II USM lens is scheduled to be available in December 2011
Canon EF 600mm F4L IS II USM lens is also scheduled to be available in December 2011