This was originally logged as an ER in the old case tracking system but that has since been retired.
Salesforce now supports group by syntax through their query language SOQL. The Connect XE ODBC driver currently performs all group-by operations on the driver client side. Would be great if Progress and also push down the group-bys to Salesforce. Salesforce currently has a constraint where they do not yet support returning grouped result sets that are bigger than 2000 rows (http://www.salesforce.com/us/developer/docs/dbcom_soql_sosl/Content/sforce_api_calls_soql_select_group_by_considerations.htm) . So this limitation might still require some group by cases to be handled on the driver client side