In 13w03a, Redstone dust has been renamed to Redstone (I think) and as a result, the sprite for Redstone dust (#0055) in the bottom item selection area looks like a piece of code. when placed however, it still results in redstone, just like normal.
(in the screenshot, it's the bottom bit with the item selection area that shows the glitch.)

How to reproduce

1. Type /give (yourself) 55
2. That's basically it, put if you want to see the full sprite, press the Q button to throw.