Virtualization, three ways
The bigger deal is VM-hosted applications. Previous to this feature, XenApp provided two ways to deliver an application to a client: through simple server-hosted applications and desktops and through application streaming. Server-hosted applications use the classic Citrix display-only delivery method, whereas application streaming is a way to use the client's processing power to run the application as if it were installed natively on the client, without the need to actually install the app. (See "Application and desktop virtualization under the hood.")
VM-hosted applications are installed on a server-hosted virtual desktop instance (not on the XenApp farm server) and delivered to the client through the same ICA protocol as classic XenApp applications. This provides a means to deploy apps seamlessly through XenApp that would otherwise not be good candidates for virtualization.
For example, perhaps you have a farm of XenApp servers with a variety of applications installed for traditional server-hosted app delivery. You may also be serving a few streamed applications that can be run by clients capable of supporting them, but there might be some apps that simply don't play nice under either solution. By installing the software as VM-hosted applications, you can run them side-by-side with server-based and streamed applications and manage them through XenApp. In addition, they only consume a single license for all sessions delivered to a single user, regardless of source. To some, this might be the final requirement to move toward a XenApp solution.
There are a few caveats, such as the fact that it's not possible to access a full desktop of a VM -- only the applications. Also, using VM-hosted applications requires a new set of infrastructure components: namely, a server virtualization deployment. Alongside the XenApp server farm, a new farm of VDI systems must be built and maintained with either VMware, Hyper-V, or XenDesktop virtualization products. It's a welcome addition, but necessarily requires a significant resource investment.
Neighborhood watch
One potential gotcha with XenApp 5 FR2 is that some older clients -- particularly those found on embedded thin clients -- cannot access what was previously known as the Citrix Program Neighborhood as they did in the past. They can be used to connect to one or more XenApp servers themselves, but will need to be upgraded to the new Citrix Receiver client to fully realize all the potential of the newer XenApp releases.
Citrix Receiver is essentially a plug-in manager that corrals all the access components. The online plug-in used to connect to hosted applications; the offline plug-in used for application streaming; the secure access plug-in, which is essentially an SSL VPN for remote application access; and the Dazzle plug-in, which (when it becomes available) will allow large XenApp installations to publish an application store of sorts for their users. The Dazzle plug-in looks quite interesting, offering a list of available applications that users can select depending on their access rights.
Citrix XenApp 5 Feature Pack 2
Cost: XenApp Platinum costs $600 per seat with a one-year software subscription; annual renewals cost $75 per seat. XenApp Enterprise costs $450 per seat with $50 subscription renewals. XenApp Advanced costs $350 per seat with $45 subscription renewals. Other plans available for smaller installations.
Platforms: Windows Server 2003 or Windows Server 2008