This should work nicely for those that want to wait to deploy XP SP3 a little longer but need to connect to Server 2008 TS Remote App. Link is at the bottom of brief overview.
Description of the Remote Desktop Connection 6.1 client update for Terminal Services in Windows XP Service Pack 2
Article ID: 952155
Last Review: June 24, 2008
This article discusses the Remote Desktop Connection (RDC) 6.1 client update that helps you use the new Terminal Services features. These features are introduced in Windows Vista and in Windows Server 2008 and are available from a computer that is running Windows XP Service Pack 2 (SP2).