MSDN blog article about RDS improvements in Windows 7 and Windows 2008 R2.

http://blogs.msdn.com/rds/archive/2010/02/05/announcing-the-remote-desktop-protocol-performance-improvements-in-windows-server-2008-r2-and-windows-7-white-paper.aspx

Here is the link straight to the document that shows some of the bandwidth improvements that have been made and MULTI-MEDIA REDIRECTION in RDP 7.0.  For LAN environments RDS is a usable protocol.

Remote Desktop Protocol Performance Improvements in Windows Server 2008 R2 and Windows 7