Where did my "Default Group" preference go?

In iOS 4.x.x, I remember having a preference in:

Settings > Mail, Contacts, Calendars > Contacts

that would allow me to select a Default Group.

Now that I've upgraded to iOS 5, that preference is no longer visible.

Was it removed? Moved? Do I have to have a specific setup in order to have that preference available?

I need to select a "Default Group" in order to reproduce a bug reported by a beta tester, so it'd be handy to be able to set this preference.

In iOS 5.1, you can define a "Default Account" for Contacts in Settings > Mail, Contacts, Calendars. Scroll down until you see a Contacts heading; Default Account is at the bottom of that section. This setting will affect where new Contacts created on the iPhone are placed.