VMware published a technical paper titled: Integrating VMware View and VMware ThinApp with Citrix XenApp which describes how to integrate an existing Citrix XenApp installation with VMware ThinApp and VMware View.
The discussion is focused on the presentation of ThinApp virtual application through XenApp Servers to users on VMware View virtual desktops.
The paper includes an interesting comparison between Application Presentation, Application Streaming and Application Virtualization which highlights the differences in Citrix application virtualization and VMware ThinApp application virtualization.