Voici quelques liens au sujet de SQL Server 2008 R2

Éditions :
http://www.microsoft.com/sqlserver/2008/en/us/editions.aspx

Comparaisons entre éditions :
http://www.microsoft.com/sqlserver/2008/en/us/editions-compare.aspx

Nouveautés :

http://www.microsoft.com/sqlserver/2008/en/us/R2-editions.aspx

Synthèse (pdf) :

http://download.microsoft.com/download/7/B/6/7B65BDD8-9D5E-42A5-A8AA-AD61FD8265E2/SQLServer2008R2EditionsDatasheet.pdf

Express :

http://www.microsoft.com/express/Database/

http://www.microsoft.com/sqlserver/2008/en/us/express.aspx

Plaquette commerciale :

http://download.microsoft.com/download/a/c/a/aca65fab-dd31-4caf-af6a-34fe3f8dd074/SQLServer2008_Brochure.pdf