Quote fromI love this idea, I've been streaming it for some friends of mine and they're getting a kick out of watching me get the crap scared out of me by creepers. XD I've convinced one to get Minecraft thanks to this, once she gets a better computer.
I have a problem though, I can't seem to get any animals to spawn. I'm playing 1.1, so the island should be big enough to begin with, and I even made it a little bigger just to make sure... I have plenty of grass and it's all lit up, I don't know why I can't get anything to spawn! The center of the island is mostly grass at this point, and I have what will be my animal trap set up on the far side of the island from my house, which is also all grass and all lit.
I haven't tried it yet today since the patch. We'll see if that makes a difference, although I don't know why it would.
The spawning algorithm (distance wise) works the same for passive and aggressive mobs... they won't spawn within 24 blocks of you.