Currently I am involved in the upgrade of Sql Server 2005 databases to Sql Server 2008. I did an inplace upgrade on the SQL Server 2005 Database to 2008, the whole process was seamless. Prior to upgrading i stopped replication and dropped all publications and subscriptions. During this upgrade process i had to upgrade SSIS packages in 2005 to 2008. In SSIS 2008 there is a upgrade wizard which helps one to migrate 2005 packages to 2008.
When I opened up BIDS(Visual Stusio 2008) and selected my SSIS 2005 Solution, the upgrade wizard popped up.
When I clicked the Next Button, it came up with the list of packages which needed to migrated. The window had three columns Existing Package names, upgrade package name and passowrd. In case the upgrade package name needs to be changed it can be changed here.
In the next screen is where there is a couple of important options. One of the things that has changed between ssis 2005 ans ssis 2008 is the connection strings to use new provider names. There is a checkbox which provides the option to do the conversion by the wizard itself. Having this box checked is highly recommended, this would make the upgrade process a lot more easier. There is a option to validate pacakges after upgrade and one for backing up original packages.
In the next screen one gets a summary of what needs to be done, once you hit finish the upgrade process starts and provided warning messages/errors once it is complete.
One thing i noticed after the upgrade was if i were using configuration files from SSIS 2005 in SSIS 2008, in some cases i got a XML badly formed error when i executed the package in SSIS 2008. In such cases i recreated the XML config file in SSIS 2008 environment.