The ConfigMgr 2012 Package Conversion Manager (PCM) tool allows administrators to convert their legacy SCCM 2007 packages and programs into the new ConfigMgr 2012 Application and Deployment Types. This applies for all legacy packages apart from virtual APP-V packages that will automatically be converted to the new application model during the migration process. Once your legacy packages have been migrated and you have installed the Package Conversion Manager utility, then it is just a matter of analysing your packages in order to determine which readiness state it is in, and then converting your packages.
There are still a number of bugs in the RTM version of the PCM tool but all in all it works well.
It is worth noting that any legacy packages that have been configured to run another program first will only create the CM2012 Application Dependency if the program is in a different source Package ID. IE. “ Package with program dependent upon another program in the SAME package will not have that dependency converted” (from TechNet). To get around this you can just manually create the dependencies once you have converted your packages to Applications.
For completion of the post, Please read http://blogs.technet.com/b/configmgrdogs/archive/2012/04/28/package-conversion-manager-pcm-in-configmgr-2012.aspx
