[Vomit Stain]

I've only had mine since 3Nov08 and its cracked through on the right side and starting to split on the left.
If you will look at the screen side of your 'book there are two little tabs which will line up with the cracks. Looks like a design oversight.
Carrying the laptop in a tight fitting case would probably accelerate the cracking. I carry mine in a camera bag almost daily. Its pretty tight in there.
The Marware pads might help but I doubt it would by much. Its probably better that the plastic cracks sooner as it will still be under warranty.
I'll be taking mine in this Friday.