If you use the extrude brush on the top or bottom of a block, it works as intended. However, if you aim at any other face of a block, the extrude brush will behave as though you clicked the face 90 degrees counterclockwise of the one you actually clicked. This bug is present regardless of your brush size.

You can test this by using extrude on a block in your voxel list: if you rightclick the face that's facing you, gunpowder will extrude to the right and arrow will extrude to the left.

This bug renders the extrude brush rather useless, except in those cases which call purely for vertical extrusion.

The disc face and voxel disc face brushes is also affected by this issue. A fix would take mere minutes and restore functionality to a wide array of brushes. Please update your bukkit references!