WPF = Windows Presentation Foundation.
WPF is the latest in desktop app development in .Net. It features markup based layout much like asp.net. The markup language is XAML. It provides a new way to develop desktop applications keeping UI and logic separate.
Check out www.windowsclient.net for details on WPF.
WCF = Window Communication Services
WCF is used to communicate between different applications with stuff like services. It is much like web services, but is much more robust and configuration enabled. WCF web services can be configured to act like asmx webservices, or use json or something else. Anything that represents a service can benefit from WCF, such as web services, windows services etc.