George is a dev/architect who has spent over eight months building a complete implementation of WS-ReliableMessaging to run on WSE 3.0. The fruits of his labour are an extensive reference example that can be downloaded from here. It persists messages to SQL Server and supports both direct (both ends up, available and connected) and queued ( neither end has to be available when the message is sent) approaches to reliable messaging.
WS-RM will not be part of the WSE 3.0 product, however this implementation shows you how to build reliable messaging into your application and being source code you can extend this as much as you want. Hearing feedback on issues and bugs with this implementation is always desired and the WSE newsgroup or WebServices Forum are the best places to do this.