Region formats on 1.1.1 - icudt34l.dat
1.1.1 allows you to select a region format for displaying dates, times, numbers, names of days of the week and months, phone numbers etc. This means you no longer need to manually edit UIPhoneFormats.plist. However, currently you cannot mix-and-match the various aspects of a region format. For example, if you set region to Australia, your phone numbers will be displayed in the correct Australia format, but your weeks will have to start with Sunday, and dates will have to be displayed as dd/mm/yyyy.
In order to customize a locale, you will need to edit the internal database of locale settings. They are stored in the ICU data file (/usr/share/icu/icudt34l.dat). Go to http://icu-project.org/ for more information regarding ICU and its data file. I have tried to recompile this data file (I want weeks to start with Monday when using the en_AU locale), but SpringBoard seems to crash if I replace the original icudt34l.dat with my own. I'm not at all familiar with ICU, so I might've made a mistake somewhere. Anyone willing to look into this a bit deeper?