Yeah, it affects all xboxs manufactured prior to Jan. 13, 2004 in europe and 2003 in the US
(which incidentally is 3/4 of M$ userbase).
Mind you, for the more paranoid amongst you heres some thoughs
1) Pre release Xbox360 bumph, what better way to get the name and address of pretty much EVERY current Xbox user to target them for the sequel
2) (and rather more insidious) Could it possibly tie the Eeproms (which contains your Serial number) that have been banned from Xbox Live to an address, thereby letting m$ know EXACTLY who's chipped their consoles?
Unlikey IMHO, but certainly possible