Precisely. In a western culture, 666 holds great negative connotations - which is similar to the number 4 in asian cultures.
I seem to recall that Intel (or some other computing company) changed a clock frequency from 666mhz up to 667mhz - because they didn't want to bring in the controversy and possible backlash from trying to advertise a clock frequency with "666" in it.
Anybody remember when that survey leaked about 4 years ago and it contained possible names for the "Xbox 2"? Here's those possibilities again for completeness sake...
Xbox 247
Xbox 360
Xbox 2
Xbox E
Xbox EV
Xbox FS
Xbox HD
Xbox NE
I'm sure their marketing will probably go in the same direction as last time. Not that any of these will be used, but it gives some indication of what they may consider.