Canon Rebates Extended
The Canon rebate program that was set to expire at the end of May has been extended until the end of June. This is the double up savings program if you buy a camera body along with a lens. There are also instant rebates on lens purchases only.
The 5D Mark III isn't found in stock in too many places, so at least you get an extra month if you've been waiting to take advantage of the rebate when buying a 5D3.
Sigma Lens Rebates
Sigma has rebates going on until July 31, 2012. Visit B&H for more.
Canon EF 500 f/4L IS II & EF 600 f/4L IS II Availability
Various smaller retailers have received lenses. I know of a couple of 500's that appeared in Toronto, and I received my 600 today.
I know B&H is expecting a shipment this week, however there is a preorder wait list. They expect the first 2 shipments to cover what is already preordered. I am unsure about the status with Adorama.
If you're a retailer and get a 500 or 600 in stock that isn't spoken for, please let me know and I can let the readers of CR know.
5D Mark III Stock
Stock of the 5D Mark III is low at the moment. Shipments for the camera should start arriving near the end of this week. I'm waiting to hear from the large retailers.