SELECT  name
FROM    msdb.dbo.sysdtspackages90
WHERE   CAST(CAST([packagedata] AS VARBINARY(MAX)) AS VARCHAR(MAX)) 
    LIKE 'servername\instancename';

;WITH XMLNAMESPACES ('www.microsoft.com/SqlServer/Dts' AS pNS1,
  'www.microsoft.com/SqlServer/Dts' AS DTS) -- declare XML namespaces
SELECT c.name,
   SSIS_XML.value('./pNS1:Property[@pNS1:Name="ObjectName"][1]', 
    'varchar(100)') AS ObjectName,
  SSIS_XML.value('./pNS1:Property[@pNS1:Name="Description"][1]', 
    'varchar(100)') AS Description,
   SSIS_XML.value('pNS1:ObjectData[1]/pNS1:ConnectionManager[1]
/pNS1:Property[@pNS1:Name="ConnectionString"][1]', 'varchar(MAX)') ConnectionString
FROM  
--
( SELECT    id ,
                    CAST(CAST(packagedata AS VARBINARY(MAX)) AS XML) PackageXML
          FROM      [msdb].[dbo].[sysdtspackages90]
        ) PackageXML
        CROSS APPLY PackageXML.nodes('/DTS:Executable/DTS:ConnectionManager') SSIS_XML ( SSIS_XML )
        INNER JOIN [msdb].[dbo].[sysdtspackages90] c ON PackageXML.id = c.id 

WHERE SSIS_XML.value('pNS1:ObjectData[1]/pNS1:ConnectionManager[1]
/pNS1:Property[@pNS1:Name="ConnectionString"][1]', 'varchar(MAX)') LIKE '%data source%'