BBC America has announced that their new BBC America HD channel will launch in July with the HD broadcast of Torchwood: Children of Earth and the latest Doctor Who special, Planet of the Dead. Torchwood: Children of Earth will air on BBC America HD and BBC America on five consecutive nights, beginning on Monday, July 20. Planet of the Dead will follow on Sunday, July 26. (As previously announced, the 2008 Christmas special, The Next Doctor, will air on BBC America on Saturday, June 27.)
It is not known whether earlier plans for "Children of Earth" to be aired on the same day on BBC America and BBC One are still on track. British television channels traditionally announce their schedules closer to broadcast date than American channels do, so the UK broadcast date for "Children of Earth" will probably not be confirmed for several weeks.
Full details for the launch of BBC America HD, including broadcast times and information about "Being Human" and "Primeval", are available here and here.