meta-Diffing a running machine

[Philip Prindeville]

I was wondering if there's a handy way to look for files
on a machine (like /etc/hosts, /etc/passwd, /etc/sysconfig/*, etc)
that have been modified relative to the installed RPM's.

Since files installed via RPM have MD5 checksums, it shouldn't
be too hard to find tweaked files, right?

I recently realized that I have no easy way to isolate and summarize
the machine I currently use versus its initial state "out of the box".

What tools are available?

Thanks,

-Philip