In response to @mariodebian's comment (#6): Using the karmic version of aptitude (0.4.11.11-1ubuntu6), files in /etc/preferences.d are ignored even if they have the .pref extension.
In response to @mariodebian's comment (#6): 11-1ubuntu6) , files in /etc/preferences.d are ignored even if they have the .pref extension.
Using the karmic version of aptitude (0.4.11.