Bukkit

In the sourcecode, a number of blocks are added as protected or transparent.

Protected:

• Chest
• Furnace
• Brewing stand
• Dispenser
• Burning Furnace
• Jukebox

Transparent:

• Air
• /* Misc */
• Cake Block

• /* Redstone Material */
• Redstone
• Redstone Wire

• /* Redstone Torches */
• Redstone Torch Off
• Redstone Torch On

• /* Diodes (Repeaters) */
• Diode Block Off
• Diode Block On

• /* Power Sources */
• Detector Rail
• Lever
• Stone Button
• Stone Plate
• Wood Plate

• /* Nature Material */
• Red Mushroom
• Brown Mushroom

• Red Rose
• Yellow Flower

• /* Greens */
• Long Grass
• Vine
• Water Lily

• /* Seedy Things */
• Melon Stem
• Pumpkin Stem
• Crops
• Nether Warts

• /* Semi-Nature */
• Snow
• Fire
• Web

• /* Lava & Water */
• Lava
• Stationary Lava
• Water
• Stationary Water

• /* Saplings And Bushes */
• Sapling
• Dead Bush

• /* Construction Material */
• /* Fences */
• Fence
• Fence Gate
• Iron Fence
• Nether Fence

• /* Ladders, Signs */
• Ladder
• Sign
• Sign Post
• Wall Sign

• /* Bed */
• Bed Block
• Bed

• /* Pistons */
• Piston Extension
• Piston Moving Piece
• Rails

• /* Torch & Trapdoor */
• Torch
• Trap Door