Announced at the Microsoft //build conference:
A data structure, implemented as a new 'COLR' table in OpenType, breaks down the base glyph into a separate set of glyphs, each with its own z-order and single color reference. The color references are handled has palette indices, with a separate table, 'CPAL' in OpenType that resolves the RGBA colors actually used for the glyph.
Video here: http://channel9.msdn.com/Events/Build/2013/3-191
Original announcement on Typophile: http://typophile.com/node/104174