Canon, PLEASE sort out your naming conventions...
I think I understand it: number after D was mega-pixel count (with an extra zero on the end), but number before the D is more in line with their film SLR naming convention outside North America: the bigger the number, the cheaper the camera. (if I remember right, Elan 7 is EOS 30, Elan 2 was EOS 50, the Rebels are even higher numbers). It seems that from now on the numbers will all be before the D, since features other than MP are becoming the main marketing disinctions in a sea of 6MP DSLR models.
What I want Canon (and Nikon, Epson and others) to sort out is the confusing practice of having one model name for the US (and maybe Canada) but another for the rest of the world, with the "rest of the world" names usually more systematic and numerical, while the US names are more often "catchy", probably invented by marketing consultants.