Provide default value to be used for all existing nodes.

This applies to a few of the modules so I put this under general.

When creating a new field for a content type, all existing nodes should be updated to reflect the default value of the new field.

A case in point is http://drupal.org/node/167111 where a new field "display age" is added to content type and should be checked by default. All existing nodes though default this field to unchecked.