I use a slightly different method to avoid some of the entitization problems FOR XML brings with it. Technically it is an undocumented method that I know of but I have not had trouble with it since SQL 2000 and I know of some other techniques that leverage it without trouble too:

DECLARE @SQLCmd NVARCHAR(MAX) = N'';

-- instead of using FOR XML just append the conjured string from each row to the same variable

SELECT @SQLCmd += 'EXEC sys.sp_rename ' + --

'@objname = N''' + SCHEMA_NAME(tab.schema_id) + '.' + tab.name + ''', ' + --

'@newname = N''' + tab.name + '_' + CONVERT(VARCHAR(10), GETDATE(), 112) + ''', ' + --

'@objtype = N''OBJECT'';' + -- OBJECT

NCHAR(13) + NCHAR(10)

FROM sys.tables tab;

-- show the entire variable contents as an XML document...no truncation like with PRINT

SELECT @SQLCmd AS [processing-instruction(query)]

FOR XML PATH(''),

TYPE;

-- when ready, uncomment

--EXEC sys.sp_executesql @SQLCmd;