After the last snapshot I started creating a texture pack, and adding some subtle animations to some of the blocks. For each of them, I created the associated [block].txt file. After upgrading to 13w09, the blockRedstone no longer functions, and is replaced by the "missing texture" block.

Other custom animations (i.e. the nether portal) still function. Perhaps the issue is with blocks that aren't originally animated? Both the png and definition file that were previously working are attached.

Replacing the texture with a single 32x32 png and removing the animation definition allowed the texture to appear in-game again.