DeltaRPM is a tool that generates RPMs that contains the difference between an
old and a new version of an RPM. This makes it possible to recreate the new RPM
from the deltarpm and the old one. You don't have to have a copy of the old
RPM, as it can also work with installed RPMs. The package also contains tools
for creating and applying delta ISOs.

WWW: http://freecode.com/projects/deltarpm/