Thoughts
IIRC, an unarmed attack and a natural attack are different. So, if you are a level one monk and you wild shape into a dire bear you can either take your monk attacks/damage OR the bear’s.
We have always thought of it a ‘wielding a non monk weapon’ (in this case the weapons are ‘claws’ and ‘bite’). You are proficient (because of the druid levels), but you can’t flurry / stunning blow because they are not monk weapons.
On the other hand, if you use the monk damage / attacks, you DO get that huge strength bonus, not to mention all that natural AC.
Sounds fun.
Of course, as a DM, you would have to do some serious explaining why your wild guardian of the wood spirit suddenly decides to become a monk (hard core lawful, controlled).
I, personally, don’t let people pick up monk (or sorcerer) mid-game unless they actually do something in game for it; such as going to a monastery and study for a few years. But that’s just me.
-Tatsu