Symbols on the Wall Push Maya Writing Back by Years
Native Village News 2006
Guatemala: A writing script discovered at San Bartolo last year is clear evidence that the Mayans were writing more than 2,300 years ago. The newly discovered script--a vertical column of 10 glyphic words--was written 600 years earlier than any currently deciphered writings.  Archaeologist Boris Beltrá was exploring deep in the ruins of a pyramid below a mural chamber. There he came on the Maya glyphs painted in black on white plaster. A scribe apparently drew the characters along a pale pinkish-orange stripe as a guideline. Radiocarbon analysis dated the words to as early as 300 B.C.  Dr. William Saturno said the glyphs might be referring to nearby art which includes a painted image of the maize god. But only one symbol, meaning "ruler," "lord." or noble person, has been deciphered. 
http://www.nytimes.com/2006/01/10/science/10maya.html?pagewanted=all