In 1924, at Glozel, France, a French boy discovered an archaeological site on his family's farm, which turned out to be the opening to a tomb. The story became a major French scandal when the site was declared invalid. Now, after 75 years, the findings have finally proven genuine. What was found was a collection of bricks and inscribed tablets, two paring knives, two small axes and two stones bearing inscriptions that have been shown to date from 10,000 to 15,000 years ago.
Below is a representation of the French Glozel plate, along with pebbles of the Magdalenean Era (14,000 B.C. approx.)

Have the meaning of the symbols on the tablets been discovered, and if not is anyone working on this code???

As far as I know, there isn's any attempt to desipher it. In one website I read that some researchers believe that the characters on the plate are similar to greek or minoan characters, but I don't know..
I mean, the "X" character was greek, ok so far, but the symbol of two crossing lines (X) can be quite easily "invented" if you know what I mean. Same goes for other symbols, like "O", "I", "V", etc.