Display entries by Category (Category in Super Table)
Not sure if you're still looking for an answer, but relation support has just been added to Super Table 0.3.7. Previously, relations wouldn't work with Super Table, as its a little bit of a special field, having sub-queries to perform for relations (each row).

You can now query fields just like Matrix:

{% set reverseRelatedElements = craft.supertable.getRelatedElements({
 relatedTo : {
   targetElement: entry,
   field: 'superTableFieldHandle.columnHandle'
 },
 elementType : 'Entry',
 criteria: {
   section: 'someSection'
 }
}) %}