FYI, I just bought a 5D Mark III body from Beach Camera and emailed them to ask if the bodies they are sending out have the light leak issue, as I saw in a previous thread that they all of the sudden started shipping before anybody else. Their response to me was, "According to Canon, the new cameras that we have just received today do not have the light leak issue." So I would suggest buying from them if you're in a hurry, as I was. They had a decent amount on eBay that were shipping immediately and I was able to swoop one up quickly on Friday. Shipping estimate was May 1-7.
EDIT: I don't see them on eBay anymore, so I don't know if they sold all of them or what the case is, but the fact that they are getting the new shipments in is a good sign for all vendors!