I have a scenario where a build generates a scoring number (in our case, it's a code coverage percentage). We'd like to consider having a check in a build to compare that coverage with the previous build (immediately previous build) and make decisions about that (flag a warning message, notify someone, fail the build, something like that) based on the results of that.
It gets hairy once we start talking about branched builds too (just what is the previous build/artifacts, for example), but it's possible we may only require that on certain branches.