SQL Server 2008 R2 Enterprise Edition will still allow multiple instances
Over a number of months I have had students on courses and members of the community express concerns over the new release of SQL Server 2008 R2 Enterprise Edition. They have been given the impression that with the new release they would only be entitled to 1 instance per processor license due the release of two new editions in SQL Server 2008 R2 known as Data Centre Edition and Parallel Data Warehouse Edition
Being at the MVP Summit last week gave me the opportunity to speak directly with the SQL Server team who led me to a resource that confirms that SQL Server 2008 R2 Enterprise Edition will still allow multiple instance of SQL Server. Specifically 25 instance per processor license. While this is lower that the 50 instance that are currently allowed in SQL Server 2008, I know that this news will certainly ease the concerns that some of you, who have asked this question.
You also have the ability to run 4 vurtual machines on this edition.
The link for this information can be found here
http://download.microsoft.com/download/7/B/6/7B65BDD8-9D5E-42A5-A8AA-AD61FD8265E2/SQLServer2008R2EditionsDatasheet.pdf
If you require more instance or virtual machines, then consideration should be given to using Data Center Edition of SQL Server 2008 R2.
More information can be founnd here
http://www.microsoft.com/sqlserver/2008/en/us/R2-editions.aspx
Thanks
Chris