Pronounced 'kyubey'?
Split spiller and register allocator thanks to SSA form. (Simpler and faster than graph coloring.)
IMHO the fixation on graph colouring really held back the development of compilers. SSA was known in the late 80s but for some reason everyone thought graph colouring was the Right Way To Do It, and it only took until the turn of the century for that sentiment to change.