Arduino, Electronics and Robotics Experiments - also Raspberry PI and Beaglebone.
Once in a while l do product and book reviews.
For what it's worth, I was able to place a preorder with Newark (the US branch of Farnell) using part number 83T1943 even though their main page only provides a 'register your interest' link. However, the order status says that the board isn't expected to ship until May 11. . .