Steps to reproduce:

1. Create one or several custom fields in JIRA and create an issue that uses said fields.
2. Create a page in Confluence and add the JIRA Issues Macro and specify the custom fields under Field Columns.
3. The macro will display whatever contents are in the 'stringvalue' column of the customfieldvalue table.

For cascading fields, it will display two numerical values referencing the customfiledoption table. For free text fields, an empty set is returned.

Edit: (March 2, 2010) Affects and Fix Version/s will also display a referential numerical value from the database table in place of the actual version number.