Yes - Spectacled (Chester), Malayan Sun (Colchester), American Black (Woburn). Quite likely I'll make it to Whipsnade (Brown/Sloth) and Dudley (Asian Black) before the year's out, so will hopefully make six but probably not going to make it to Scotland for Polar or Giant Panda so full set looking unlikely!
(if you count overseas zoos as well I'm only missing Giant Panda in 2012 now, however!)
I've an idea, as these are the last ones in the UK rather than shooting them for sport in the US isn't it possible to import a few over to the UK rather than ending their lives for no good reason.