When you need to change the location that you have been saving all your package source files, you will then need to update all the existing packages and applications to point to that new location.
(Note: See here to read what happens when you do update all your source locations)
This is fairly simple for Packages, but is a bit more complicated for Applications (more…)
A quick link for reference to what happens in Configuration Manager when all you change is an application or packages source path, but the file contents are still the same?
This is an important point to understand as it does NOT resend all the files back out to DP’s again. This means you can change where you keep your master software repository without having to worry about massive network impacts.
This blog post has an excellent explanation: http://blog.configmgrftw.com/content-distribution-myth/
Annoying stuff I figured out (or am trying to) 