Perhaps I am confused or simply don't understand the question or have a bad reference source.
The whitepaper "SQL Server Consolidation with SQL Server 2008"
Writer: Martin Ellis
Reviewer: Prem Mehra,Lindsey Allen, Tiffany Wissner, Sambit Samal
Published: March 2009
Applies to: SQL Server 2008
page ten, lists
Edition Maximum instances
SQL Server 2008 Standard 16*
SQL Server 2008 Enterprise 50*
*Depending upon available system resources and workload