Howto {easily} revert or downgrade when things go wrong ?

[David Timms]

Hi,

What is the best way to cause yum/rpm to downgrade or revert to earlier 
package versions, when I find that things have stopped operating properly ?

Eg. FC3, yum update at some point openldap-server broke {but where?}. Is 
there an option /plugin/ util to:
1. revert to all package version as they were installed at a date.
2. revert a problem package {and it's dependencies} to what they were on 
a certain date.
3. revert to previous version of a package {and it's deps} (ie not have 
to know / guess the date).

Of course, the bigger answer is bugzilla it and help fix it, but that 
dont fix the here and now.

DaveT.