Also, wouldn't a light sensor be poorly placed in the exact middle of the top bezel? You have to figure that people are going to be holding this every which way, but most of the time when in landscape mode, that section would be covered up.
Then again, this whole camera thing seems crazy to me.
With something of this size, as an engineer, I would most likely put FOUR light sensors in the device, one in each corner. Then use 3 out of 4 voting to determine if it should be dimmed or not. Apple has done this with the MBP (at least the version I have, 2008). There is a light sensor under the left AND right speaker grills, you have to cover BOTH of them to get it to dim, one or the other won't cause it to dim. You do this so that if it is partially covered, maybe by someone's hand holding it, or typing on it, it doesn't accidentally dim. In the iPhone and iPod Touch, it doesn't matter as much because you hold it differently.
As for camera things. There are obviously iPads WITH cameras, and iPads WITHOUT cameras. One of these is an engineering unit, meaning it was built up for testing and development purposes, but not really meant to be in the public's hands. [note, both could be engineering units, but I'll go with one is are production units] BUT what we don't know, is which is which.
It could be that the one without camera is the production unit, version 1.0. Where the one WITH a camera are the engineering units for version
2.0. That is another possibility, I'm sure they are already working on the next gen hardware.
We'll find out in about 60 days, till then, or until Apple says something different, everything is just speculation.