Pretty sure all Shimano shifters and derailleurs are compatible.
True, until shimano changes pull ratio, which is exactly what they have done with the new 10 speed stuff, at least with the XT.
Just to let you know in case you were looking forward for the newer derailleurs to come out....like me!
"Blessed is the man who, having nothing to say, abstains from giving us wordly evidence of the fact." George Elliot