Xendesktop Aero Effect

With XenDesktop 5.5 you can now deliver the Windows 7 Aero Effects like
Glass effect
Thumbnail preview
3D effects
Shadow Effects
and more

There are some pre-reqs for this to work for this to work though.

This is the extract from a Citrix Blog
Also /CTX130849 explains there needs to be a miniumum 5fps by default but this can be changed

Aero Redirection requirements

This first release of Aero Redirection is designed for “rich clients” (essentially, PCs). Client computers must meet the following software, hardware, and video card minimum requirements to be able to receive Aero graphics:

• 2 gigahertz (GHz) 32-bit (x86) or 64-bit (x64) processor non-mobile (3 GHz recommended)
• 1.5 gigabyte (GB) of random access memory (RAM)
• DirectX 9 class graphics card that supports Pixel Shader 2.0 in hardware with 128-megabyte (MB) video memory
• DirectX 9 runtime (Windows XP, Vista, Windows 7). ThinPC and XPe are supported if the DirectX 9 runtime binaries have been preinstalled.
• Connection bandwidth of 3 Mbps available per user (Broadband 6 Mbps recommended)
• Citrix Receiver 3.0 for Windows

Aero Redirection is only available with XenDesktop 5.5 on Windows 7 VDAs through VDI deployment. It is supported on the following hypervisors:

• Citrix XenServer 5.6 and above
• VMware ESX
• Microsoft Hyper-V

VDAs must be configured with minimum 1.5 GB of RAM without overcommit.