MtH

I can confirm this, though it seems like the textures are only flipped on the North and East sides of the block. (viewed from South and West)

Confirmed! I was trying to get a cow to go into my farm but it wouldn't stop running.

Fixed for me in 1.5.1, using ATI Radeon HD 4600 Series.

That's because the bug was always in the game. Though with the new texture pack format the problem is a LOT more severe.

Here you can clearly see the lines, especially on the black wool.