Physical Server or a Virtual Machine SQL Server?
If you are using SQL Server 2008 R2 RTM or older then there is a CMD Command "SYSTEMINFO" which has information about System model.
OR
If cmdshell is enabled on instance then you can execute it from SQL Server Management Studio.

DECLARE @result int
EXEC @result = xp_cmdshell 'SYSTEMINFO'



  System Manufacturer:       VMware, Inc.
  System Model: VMware Virtual Platform


New columns (virtual_machine_type, virtual_machine_type_desc) in DMV sys.dm_os_sys_info are introduced in SQL Server 2008 R2 Service Pack 1 

http://blogs.msdn.com/b/sqlosteam/archive/2011/05/11/more-on-dmv-changes-in-sql-2008-r2-sp1.aspx