The following are required to enable Aero Glass in a Remote Desktop session:

On the Remote Desktop client:

Windows Aero-capable hardware and driver is required, and the following settings should be selected in the Remote Desktop client:

1) The color depth of the remote session must be set to 32-bit

2) “Desktop composition” must be enabled on the Experience tab

Please note that if Windows Server 2008 R2 is your Remote Desktop client, the default graphics driver installed is not Aero-capable. You will need to update your driver software to enable Aero Glass remoting.

On the remote computer:

If the remote computer is a Windows 7 client machine, the ability to support Aero Glass remoting is enabled by default.

If the remote computer is a Windows Server 2008 R2 machine, the Desktop Session Host (RDSH) role is required. In addition, the Desktop Experience feature, Themes service, 32 bits per pixel (32bpp), and Group Policy are required. The steps to enable Aero Glass remoting on a Windows Server 2008 R2 computer are provided later in this blog.

The operating system on the remote computer and the remote desktop client are required to be Windows 7 client or Windows Server 2008 R2. A support matrix is provided in the “Troubleshooting” section.

Aero Glass remoting support includes the following:

1) Full Aero theme, 3D animation and desktop composition support in remote sessions. This provides a “like-local” user experience.

2) The remote computer is not required to have Aero-capable hardware, so connecting to a virtual machine or “headless” server machine still provides Aero support, assuming the client machine has an Aero Glass-capable graphics card installed.

3) Aero Glass remoting is bandwidth-efficient and works across WAN.

Transitions between Aero Glass on and off, local and remote sessions are transparent to applications.

Source: http://blogs.msdn.com/rds/archive/2009/06/23/aero-glass-remoting-in-windows-server-2008-r2.aspx