I was asked what role virtual appliances speak in disaster recovery planning. I though I share my view here. Speaking for ourselfs as a smaller company: we are moving towards virtual environments not only in order to consolidate systems, but also because it is much easier to move over functionality from a failed system to another. Some of the functions (like mail gateway, firewall etc) do not even require state data, so they can simply be restored by using a generic template virtual machine.
Instantiating this is much quicker then building a machine with scripts from scratch, not to mention that we do not need to have the hardware in stock. In fact, we think about moving such functionality even to data center servers and thus be able to quickly switch between them if there is need to.
My syslog appliance could play a similar role in disaster recovery. While it probably is not appropriate to lose data (depending on use case), it may make sense to set up a new temporary appliance, just to continue gather data and provide analysis while the rest of the system is restored. Instant log analysis is probably a key thing you would like to have in your early recovery stages.