Yum-presto is a plugin for yum that looks for deltarpms rather than rpms
whenever they are available. This has the potential of saving a lot of
bandwidth when downloading updates.
A Deltarpm is the difference between two rpms. If you already have foo-1.0
installed and foo-1.1 is available, yum-presto will download the deltarpm
for foo-1.0 => 1.1 rather than the full foo-1.1 rpm, and then build the full
foo-1.1 package from your installed foo-1.0 and the downloaded deltarpm.
Presto-utils is a series of tools for creating presto repositories that
yum-presto can use.