In some cases, where I would want my armor to last longer, I'd prefer a functional Unbreaking enchantment for armor over any Protection-type enchantment....
I also saw this on 1.4.7, on an SMP server! (I didn't think to take a picture of it, though. Sorry....) I've also seen this bug occur on Survival mode (namely, on that same server) AND without mob griefing disabled.
This still occurs in even the most recent versions (up to 1.4.6pre).
Through rigorous and extensive testing of this bug, I found that, under certain strenuous conditions—the kind that could lag MineCraft to the point of crashing/freezing indefinitely (i.e.: approx. 100 Villagers and Baby Villagers being chased by about 200+ item-wielding Zombies, Villager Zombies, and Baby Villager Zombies, being in turn chased by 6-8 Iron Golems, all under the influence of Extended Speed I and II, Extended Strength I and II, Extended Regeneration I, Extended Slowness I, and other similar potion effects)—the Iron Golem bug could still occur. (Unfortunately, I couldn't reproduce the bug in that same method a second time for the purpose of taking a screenshot of it.)
Recently, I accidentally hit an Iron Golem in the head, while it was standing idly right next to a Creeper; but at the exact moment I did that, the Iron Golem attacked the Creeper. (Unfortunately, I couldn't get a screenshot in time....)
I found another bug as a result of this enchantment book bug: If you enchant a Nerfed Golden Apple (the one made with the Gold Nuggets) in this manner, it doesn't a glow to it. (See "Glowless Apple" picture above for proof.)
I think this should be made into a feature EXCLUSIVE to Creative Mode--items normally unstackable would stack in Creative Mode. This could help me save inventory space that I would rather use for other items.
I've noticed this with stairs and some slabs as well.
Shift-clicking items to remove them from your inventory doesn't work in Creative Mode if the Survival Inventory tab is opened/displayed at the same time.
A couple of times while testing this bug, I found that if I were to give a regular (adult) zombie armor and a sword, exit the world, reload it, and then kill the zombie, it wouldn't drop the items I gave it; it would only drop its normal loot. This discovery was completely accidental, but I can't seem to reproduce it anymore for some reason....
Dinnerbone and Jeb said at an earlier point in time that they fixed this bug--the real thing is, though, that (I think) they merely reduced the frequency of it happening by 80-90%. (This was probably unintentional....)
I can confirm that this bug still exists as of 1.4.4.
It's no longer possible to place the alternate double slab block (the block that uses the top/bottom texture of the stone slab on all six sides) as a result of this bug.... =(
So Zombie Pigmen can't be friendly?