I’ve been working with a company here in the Denver area and they’ve been looking specifically for this type of virtual machine catalog/pool.  The scenario is a group of Power Users who use fully provisioned virtual desktops today.  They expect to install their own applications and have these installs persisted.  In XenDesktop 4 there really was no reasonable way of delivering this (and still feeling good at the end of the day…I know it can be done with PVS…but ugly method).  Well in Citrix XenDesktop 5 this has all changed…YAY!

A Dedicated Machine Catalog is one that starts from a master/gold VM but all changes to the desktop are persisted.  The user can be assigned to this VM manually or automatically on first connection and will always then be assigned/connected to that virtual machine.  As I said earlier, for users used to installing whatever applications they want whenever they want and have an expectation of persistence of those changes…this is the pool for them!  If you can move to delivery method such as XenApp for delivery of those applications and can capture profile changes via UPM or AppSense then a Pooled Machine Catalog would be more appropriate.  The Dedicated Machine Catalog isn’t where you want to start with your users, but if you are like most large organizations some part of your end-user population will probably need it.

More information here: Choosing the Machine Type