You know as well as I, that Debian releases have code names and version numbers just like other operating systems. I will admit that people tend to use the names more than the numbers but the same could also be said of ubuntu and Mac. Which OS X "cat" are you currently running?
Sarge = 3.1, Etch = 4.0 and Lenny will be 5.0. Indeed the code name is mostly used before the release (before a number has been allocated), once released the release number is used in official documents and the code name in quotes or parentheses if at all.