According to
his own site, v.31.01 has a bug with regards to graphic tilesets which prevents him from releasing a stable update. "Until that bug is fixed, if you're desperate, try looking for temporary solutions on the forums."
So probably any temporary release thus far is just porting the old tileset into the new format, but not yet updated with new creatures or such.
Edit: d40? No idea where that came from. Version .31.