Minecraft 1.4.6, Minecraft 1.4.7
Cleanroom generated map, vanilla server.
Note that bukkit does the same
A player made a simple shop advertisement using redstone lamps near spawn.
There are no known issues except on a stripe of blocks.
177 block far to the north of the lamps the stripe capture players.
Connect to the included server, then walk to x=0, z=-180
Expect hanging your client, since the server goes fine.
MC-1692 Excessive lag on lamp de/activation across chunk borders