One of the challenges i was facing while developing SSIS packages was how to move around the packages through the different environments. There is a enable configuration option in the SSIS designer /BIDS. There are different kinds of configurations avaialble. They are:
XML file Configuration
Parent Package Variable
The options I choose were XML configuration and the SQL Server method. In the XML configuration option, In the Configuration wizard, Once has to choose the location for the XML File, Once that is done in the next screen, the properties for the different connection objects can be saved. This would typically contain the connection strings for different databases. In the final screen one can see all the different properties that are going to save in the XML file. Once this is complete the XML file will contain the important properties needed for the package. When the package is executed it uses the XML file to set the different connections. While moving across environments one has to create am XML file for QA and Production with the connection strings modified accordingly.
There are various other blogs across the web which describe the SQL Server method of configuring, In this case the configurations are stored in a table within a sql server database.