Spawn protection does not work properly, I have noticed the following issues on a vanilla minecraft server, 1.4.2 pre, with a op in the ops.txt
1) spawn protection set to 0 in the server.properties still leaves a 1x1 column of spawn protected area
2) water/lava that would be in the normal size protected area does not react properly to buckets when the spawn protection is set smaller. For instance, trying to pick up water puts it in the bucket, immediately removes it from the bucket, but does not put the block back in the world. It will also not let me place water if I am in where the default spawn protection would be.
3) Every now and then, while mining blocks near the 1x1 spawn protected area, it will not let me place blocks that are NOT in the area, but still in what the default spawn area would be. I can not reproduce 100% of the time, but it seems to happen after trying to mine blocks from the spawn area, then immediately trying to place a block next to it.