mi24k,
You shouldn't need to worry about this at all if you are publishing out an application properly.
When you publish out an application, you can add multiple Citrix Presentation Servers that can host this app so you aren't providing a single point of failure.
For example, if you publish out Word to all of your end-users; during the new publish app wizard it will ask for which servers you want to use for this application. You can use all of your citrix presentation servers or two of the presentation servers.
The end-user will not know the difference because all they would see if the Word icon.
If you lose one of your Citrix servers..it wouldn't be a big issue because Citrix will know that the server is down and route connections to the other Citrix servers.
Having said that..you will need to have either Citrix Advanced licensing to have the "load-balancing" ability.
If you need more information, just go to
and look for the Citrix Presentation(XenApp) administration guide and it will explain further.
Hope that helps.