Checksysreport is a tool targeted at people doing technical support for Red Hat Enterprise Linux boxes.
It generates a report based on a sysreport (or sosreport) archive that list third party packages, third party kernel modules as well as give a list of known bugs that are fixed in more recent version of packages available on rhn.
A sample report can be find in the following sample output.
A graphical tool, yadarh (Yet Another Day At Red Hat) is included in the client package. It let you browse erratas and changelogs between two different version of the same package without having a sosreport archive.

You will need a valid rhn login as well as an access to a checksysreport server to use checksysreport. The server stores rhn related information in a postgresql database that can be used by both checksysreport and yadarh.It also comes with a web page that let user post sysreport archives from a web browser and receive result by mail.
You can download the needed packages in the download page
You can contact me by sending a mail to pamadio at redhat.com