Someone at the office stopped by my cube with the new Weird Al Yankovic CD, Straight Outta Lynwood. Only it wasn’t just a CD, it was also a DVD. Turns out this was a DualDisc, CD on one side, DVD on the other. Neat trick.
The DualDisc article on Wikipedia has some details on this format (the DualDisc FAQ is very basic). Pay close attention to the Criticisms sections of the Wikipedia article if you have problems with a DualDisc.
Problems aside, this looks pretty cool. You can distribute one piece of media that plays CD content, DVD video content and DVD data content. I suspect the costs of producing the media are higher, but distribution and storage costs would about the same.