RHEL/CentOS - Is it possible to update packages only up to a certain release date?

It sounds like this customer should either have their own organisation inside the satellite (and you could then give them org admin rights if you so desired), OR you should clone the channels you need, and then, when they say go, you go into each cloned channel and update it (can't quite think of the terminology right now, but its next to the 'sync' button.

When you originally clone a channel, you can opt to clone it with no/all/selected errata. In 5.6 (or was it 5.5?) they added an option to clone to match a particular release. Before that, you had to use a script (unsupported?)

One work of warning though, when updating, do it though the 'Manage channels' part of the interface, not through the 'Errata' part of the interface, of you'll drive yourself nuts.

Note that Red Hat have some RHEL 5 and RHEL 6 best-practice guides for managing SOE's (Standard Operating Environments), which may be of interest to you.

eg. https://access.redhat.com/articles/1169613 (Subscriber Content)

If what you want is to have multiple machines with exactly the same packages and versions, you could use yum load-ts (yum load-transaction)

From man yum:

load-transaction

This command will re-load a saved yum transaction file, this allows you to run a transaction on one machine and then use it on another. The two common ways to get a saved yum transaction file are from "yum -q history addon-info last saved_tx" or via. the automatic saves in $TMPDIR/yum_save_tx.* when a transaction is solved but not run.