The obsidian pipe will automatically collect items that come into contact with it. Applying power from an engine to the pipe will increase the range of items it can suck to 1 block (distance has been increased to roughly 4 blocks as of 2.0.1). Redstone Engines suck up one item per pump, while other engines suck multiple items up at a time. Without the engine, the items need to touch the pipe to be sucked in.
The obsidian pipe can also extract items out of the inventory of a minecart with a chest.
Obsidian pipes will not connect to other obsidian pipes.
Obsidian pipes can not be waterproofed.
To craft an obsidian pipe, you need two blocks of obsidian and one block of glass. This makes 8 pipes.