Minecraft 13w16a recognizes my AZERTY keyboard as a QWERTY.
It works as expected in the chat window, but like a QWERTY keyboard when used to control the game (to move the player, etc.)

I only have the issue with this snapshot.
Minecraft 1.5.1 (which is in the same folder, launched by the classic launcher) isn't affected.

Stangely, I did not encounter this bug when I had to install the snapshot in a clean new "minecraft" folder with the 0.1 Launcher - (because the game was not starting, this one has been fixed with version 0.2 of the launcher).

The choosen keyboard configuration in the settings of OS X doesn't have any effect on this bug.