I was in the process of configuring TFS 2010 Beta 1 and the configuration wizard was failing on Reporting Services with error message TF255275: SQL Reporting Services could be accessed…..

Server: Win 2008 x64

Database: SQL Server 2008 x64  

The issue was my existing Reporting Services database was configured for SharePoint mode. So, use SQL 2008 Reporting Services Configuration — Database — Change Database to create a new database for Reporting Services. This should take care of the problem. To understand RS Configuration in SQL 2008 for TFS 2010, refer to "Configure Reporting Server Manually" section in Beta1 Install Guide.